for what it’s worth, i’m not able to reproduce the problem on my Pixel 3a. i switched the primary language on the Pixel to French (Canada), and then selected English as the iNat language, with Canada as the preferred place for common names. this results in English names all across the board. changing the iNat settings to use the device language or French (Canada) results in (mostly) French names. switching back to English in iNat gives me English names.
have you tried restarting the app? logging out and back into the app? restarting you phone?
you could also get the log files from your phone and send them to iNat (help@inaturalist.org):