First original 2000 and 2003 RTP are in Japanese. But there are more than one translation of each. The game interpreter wants to support any game made using any RTP but we need to know any RTP made.
Currently, these translations are known by us today:
English (Don Miguel)
English (RPG Advocate)
English (with files as DonJohn.png instead of Dungeon.png, missing 2000 RTP midi files)
English (similar as above but with character errors in some files)
Chinese (seems to be official, hongkong release)
Do you know more RTP translations/versions not listed here?