take photos of the screens and post here. if they are accessed with the custom button some of them were Fanuc screens and can probably be changed.
on my MAPPS the language is set in one of the INI files and depending on what MAPPS version you have and what language and files you have now it may be possible to just copy across and replace one file from an English version of the MAPPS software.
But first take photos of the screens so we can see what they belong to (Fanuc side or MAPPS side)
Also if you can manage it, take out the PCMCIA card from the MAPPS unit, put it into a laptop and copy out a directory of all the files in a DOS command prompt by typing DIR /S > LIST.TXT
then post the file LIST.TXT here. This will tell us what language files you have now.