The idea that there was a fully functional 5e build is just community’s misinterpretation of quotes from devs.
Misinterpretation or misrepresentation? I'd call it the latter, personally. I feel that the quote strongly implies that they legitimately tried a system that was pure 5e, and the worked outward
from there - not making any comments about what were game builds or not - that, I feel is the very strong represented implication of that quote. It's also patently not true, and a misrepresentation of what actually occurred - which is that, at best, they read over the 5e manual and set it down on paper in a bullet point form as short hand, and then went to their game engine and started seeing what they could build
into it from that list. The initial days of the game made it clear that the engine was almost entirely lifted one to one from D:OS2, and then modified
From There to have more 5e bits and pieces, and that process is still on-going. It does not support their assertion that 5e doesn't work in a video game format, and there is ample proof that, in fact, it does work very well in a video game format.
I would definitely call it misrepresentation - which is a failing on behalf of the company - and not misinterpretation, which would be a failing on behalf of consumers.