To be fair, even if "from scratch" means "download and build Chromium", that's still nontrivial to accomplish. And with how complicated a modern browser is, you can get into Ship of Theseus philosophy pretty fast.

I wouldn't particularly care what code the agents copied, the bigger indictment is the code doesn't work.

So really, they failed to meet the bar of "download and build Chromium" and there's no point to talk about the code at all.