Technical analysis shows the Saturn version uses the original Genesis/Master System ROMs. A known "patching" method involves swapping these internal ROM files with their English counterparts and updating the Saturn executable's pointers to match the new offsets. Official Multi-Language Alternatives: While the Saturn collection is Japanese-only, the Sega Ages 2500 Series Vol. 32
" : Part of the Sega Ages 2500 series, this version (Vol. 32) is almost identical to the Saturn version but . You can simply select the English version from the in-game menu. Phantasy Star Retranslation Project
Replace the Japanese files with your renamed English counterparts. Rebuild the Disc Image Sega Saturn Patcher