So you have a copy of the English Phantasy Star III rom image but you don't know English.. how the heck are you reading this page then!? Anyway, here's the spot to download translation patches for Phantasy Star III.
What you will need to use these patches:
1) English Phantasy Star III rom image in .bin format. "Phantasy Star 3 - Generations of Doom (UE) [!].bin"
or "Phantasy Star 3 - Generations of Doom (UE) [o].bin" both work. Use GoodGen to determine which version of the rom image you have.
2) An .ips patching utility