my name is Vincenzo. I am an italian guy and i have found a solution for anyone who wants to change language in Google Maps (or any other app) without changing system language. I registered only for this, I hope can help. (sorry for my bad english)
- Root, Xposed
- App Settings version 1.13
After accepting module, go to App Settings, found your app and set on "Settings". There is an option, "Locale". Choose your language (only for this app!) and save on the top , right.
My Maps now is in Italian (with Italian voice).
Tested with Moto G Titan, MM 6.0.1 - AOSP CAF