elfin mantle
It would take lots of work, and I know it's a bit of a stretch. But, what if players could hear enemy faction voices in that enemy faction's language when in proximity voice range (i.e. US faction would hear German faction speaking German). This would be done regardless of the player's actual language.
As a bonus, this could also open a Translator role to infantry.
clear grove
That would be so ridiculously hard to pull off dude
radiant tundra
Probably impossible, or very very hard to do with little to no reward. Every time someone talks, the person on the receiving end would hear German or Russian. This just creates a very one sided mechanic because German and Russia aren’t going to be understandable and Americans and Brits use English. Then one you figure out how to balance it, then you have to implement it to where the English spoken through the mic is translated to the language respective to that nation. Maybe in the next 5-7 decades this would be possible but I doubt it current day.