As for Ada working for the Chinese government where in supplemental material is this referenced? It’s never mentioned in any of the games.
Well, to be fair, it's never directly referenced, but 'Dead Aim', in context, is the biggest greatest giveaway of them all, as Bruce and Fong Ling were designed to be quick and fun versions of Leon and Ada jam packed into a simple, single game w/o any overarching story across multiple games. This was the original arc behind Ada Wong, anyway, Fong Ling was a very simplified version of her. I'm glad you mentioned the deaths of Sugimura and Suga though, because one of them probably conceptualized Ada as a secret Chinese spy but Capcom later decided to brush it off and do whatever they want with her, further putting more nails into the proverbial coffin of the series.
What Capcom decides to do with Ada in the future is a mystery though, but the original idea of Leon and Ada being twin flame agents working for rival governments is quite good and I hope they try to mend this original arc in the future but it may be too late for that because everything in the series lore wise has been a hot mess since RE4 2005.