What you describe is how the socialist market economy is. All economies are mixed, really, even the DPRK with its Special Economic Zones. Public ownership governs the large firms and key industries, while market forces govern secondary and smaller industries. This is what it means to be the principal aspect.

A note on principal aspects: I do not mean principles as in ideals or morals, but the essence of a contradiction. From Mao's On Contradiction:

As we have said, one must not treat all the contradictions in a process as being equal but must distinguish between the principal and the secondary contradictions, and pay special attention to grasping the principal one. But, in any given contradiction, whether principal or secondary, should the two contradictory aspects be treated as equal? Again, no. In any contradiction the development of the contradictory aspects is uneven. Sometimes they seem to be in equilibrium, which is however only temporary and relative, while unevenness is basic. Of the two contradictory aspects, one must be principal and the other secondary. The principal aspect is the one playing the leading role in the contradiction. The nature of a thing is determined mainly by the principal aspect of a contradiction, the aspect which has gained the dominant position.

Public ownership is the principal aspect of the Chinese economy, not private ownership. I very well understand that materialism rejects idealism, and that material conditions matter above all. That's why I identified your use of simple ratio in identifying socialism as metaphysics, the 50/50 split is entirely arbitrary and says nothing of which aspect has dominance. The fact that the large and key industries are public means that the private sector is thoroughly under the control of the public sector.

A common example is the rubber factory and the rubber ball factory, the rubber factory has total control over how the rubber ball factory can function even if the rubber ball factory makes more profits or whatnot (a problem with focusing on GDP). China does this with all of its key industries and large firms, while allowing diverse forms of ownership (including private) to fill in the gaps left by the state owned and run industry, and in turn become folded into the public sector.

Returning to my quote from Xi Jinping:

In recent years commentators both at home and abroad have questioned whether the road pursued by China is truly socialist. Some have called our road “Social Capitalism,” others “State Capitalism,” and yet others “Technocratic Capitalism.” These are all completely wrong. We respond that socialism with Chinese characteristics is socialism, by which we mean that despite reform we adhere to the socialist road — our road, our theory, our system, and the goals we set out at the 18th National Party Congress.

The CPC fully believes (correctly) that SWCC is socialism now. What SWCC is not is static. The current market distribution is not a fixed, permanent position, but something that unfolds dialectically. As public ownership is principal, and is rising, the private sector gradually grows, socializes as markets do, and is folded into the public sector. This is the path of dialectical development, from lower to higher, from quantity to quality. It has nothing to do with vibes, but instead the recognition that the character of an economy is not determined by ratio, nor by the "one-drop" rule, but by the principal aspect of the economy.

In other words, by that which is dominant in the economy via controlling the large firms and key industries, and that which is rising. SWCC is socialism now, as it develops and grows from less developed to more. Again, see Cheng Enfu's diagram:

This is entirely different from Nordic style social democracy, which, while having sizable safety nets, has private ownership as principal, dominating the large firms and key industries, as well as the state. Some social democracies even have higher public ownership ratios as a portion of GDP than the PRC, and yet their results materially are dramatically different. This is proof that it isn't just an arbitrary, vibes-based ratio, but correct identification of that which is rising and dominant in an economy that determines its character, as dialectical materialism teaches us.

Comrade, with all due respect, I suggest you pay more attention to what our comrades in China are actually saying about their socialist system that being that they consider the socialist market economy to be the primary stage of socialism. I also implore you to not make the assumption that I don't know about the materialist aspect of dialectical materialism, it's insulting. I don't pretend to be an expert, but I did write a short overview of dialectical materialism you can check out if you feel the need to vet my "diamat cred."

I'd like a source on CPC officials saying they don't have a socialist economy yet. Their officials call it a socialist market economy, because that's what best describes it. Here's Xi Jinping, in 2013:

First of all: Socialism with Chinese characteristics is socialism, not any other “ism.” The guiding principles of scientific socialism thus cannot be abandoned. Our Party has always emphasized adherence to the basic principles of scientific socialism, but adapted to the particular conditions of China. This means that socialism with Chinese characteristics is socialism, not some other doctrine.

...

In recent years commentators both at home and abroad have questioned whether the road pursued by China is truly socialist. Some have called our road “Social Capitalism,” others “State Capitalism,” and yet others “Technocratic Capitalism.” These are all completely wrong. We respond that socialism with Chinese characteristics is socialism, by which we mean that despite reform we adhere to the socialist road — our road, our theory, our system, and the goals we set out at the 18th National Party Congress. This includes building a socialist market economy; socialist democratic politics; advanced socialist culture; socialist civil harmony and ecology; all-around human development; the gradual realization of common prosperity for all people; a rich, strong, democratic and harmonious socialist modern state under the leadership of the CPC with economic construction as the center; adhering to the Four Cardinal Principles; insisting on Reform and Opening Up; and the liberation and development of the productive forces. It includes adhering to the system of People’s Congresses; the system of multi-party cooperation under the leadership of the CPC; the systems of national autonomy at the regional level and mass autonomy at the grassroots level; the socialist legal system with Chinese characteristics; and the basic economic system in which public ownership is the mainstay and a variety of auxiliary ownership systems develop alongside. These goals embody the basic principles of scientific socialism under our current historical conditions. Adherence to the socialist road demands that we fulfill them.

Capitalism is indeed not markets, but it is also not determined by simple ratio of private property to public, nor is a system with X% private and Y% public X% capitalist and Y% socialist. Dialectics rejects these frames of analysis as metaphysics. What matters is what is principle, what is rising and dominating the economy. In the PRC, the large firms and key industries are overwhelmingly publicly owned.

The private sector in China is about half sole proprietorships and cooperatives, and the rest small and medium firms. Despite making up a sizable portion of GDP, these do not control the economy, nor direct its trajectory. The basis of communist production is in large industry, not just collectivizing even the small firms before markets have centralized them. This does not mean it is necessary for private property to exist to develop socialized production, the DPRK is a good example of this (though they have special economic zones like Rason). However, it does mean that by maintaining public ownership of the large firms and key industries, socialism can be maintained. China's socialism is the socialism suited for China.

The problem with looking at simple ratio, is that this makes no analysis of how power is distributed, what tendencies are rising and which are dying away. This views production and distribution not as something that changes in identity as time moves forward, but instead as a substance in flux. In this way, it is metaphysical. When accurately contextualizing the relationship between public and private in China, it is the public sector that holds all of the power, that absorbs the private over time as the private grows and develops. Dialectically, China exists in the transitional state between capitalism and communism that we call socialism.

Harkening back to Cheng Enfu's diagram, they are in the developing and intermediate stages of socialism. They are not advanced in socialism, and likely will not be for a while. Their progress is thanks to socialism, however, built by Mao Zedong and the CPC, carried to today and interated upon as new conditions arise and new contradictions form.