I had this same issue and resolved it by doing the following…
In your default Documents folder (mine was C:\Users%userprofile%\Documents" look for Rockstar games, then GTAV and in the profiles folder look for the profile your gta is using. FILE: pc_settings.bin
(full path to mine was C:\Users\%userprofile%\Documents\Rockstar Games\GTA V\Profiles\29E9FFEC)
Move the pc_settings.bin to %userprofile%\Saved Games\CitizenFX\GTA5 and rename it to ‘fivem_set.bin’ (I renamed my original ‘fivem_set.bin’ to ‘fivem_set.bin.OLD’ so I can go back to it)
Once the new file is in place, open FiveM like normal.
The menu should now be in English (as long as your regular version of GTA is)
But wait, there’s more!
In the menu, go to SETTINGS - DISPLAY
Scroll down to the second last option which should be Language. If not already English, change to English.
Save the new setting and exit the menu.
Lastly, close GTA and go back and restore your original ‘fivem_set.bin’ in the *%userprofile%\Saved Games\CitizenFX\GTA5* folder
Restart FiveM!
I hope this works for you!