Having played zmr on north america for years, having tried hazard ops in europe and even trying the china version, I'd love to share my experience with subagames if the would be interested.
Trying the game right now, but my first suggestion is, on the character voice options, add different languages, like a spanish accent, russian, french... The current voices are simply more of the same but by adding those accents, they make the choice much more appealing, and adding words in that language makes it even better. I'll always remember "ayuda" when I was asking for help from the voice command.