The article states pretty explicitly that RCS is not what they did “a more structured alternative to RCS”

Hmm. If thats the form of the answer you're looking for, I'm confused why you asked the question. My apologies, I thought you were trying to understand a new topic you didn't have context for. I withdraw my long winded answer. Let me try again for you to your original two questions:

Article doesn’t say what they actually computed

“a more structured alternative to RCS”

or what the complexity would be for a normal computer

Your statement is factual. That information is not contained in the article.