If you're curious, their GitHib issues and website have a bit more about them: https://github.com/opencloud-eu/opencloud/issues/231

The Heinlein Group, to which OpenCloud belongs, is probably best known as the operator of the email provider mailbox.org, but also develops OpenTalk, an open source video conferencing solution.

from heise.de.

Being the owner of mailbox.org doesn't mean anything to me, but it's context. And there's more info in that GitHub issue's links.

My impression is that they know what they're doing when it comes to production ready software--I share the OPs concerns about the syncthing-fork maintainer--and they have the funding and acumen to stay in business, meaning their software will be maintained.

I can't endorse them beyond my own personal opinion though. I don't have any info beyond what a few hours of digging turned up last time I looked into them.