Hi! Can I ask you to send me some samples of your OFS3 files? I want to test them with a tool I made the last year for a fan-translation (the game was Tokimeki Memorial Girl Side).You could try asking in the programming section of the forum: Computer Programming, Emulation, and Game Modding
Probably there're python programmers in other sections too since I've seen python scripts used a lot when it comes to the PSP scene, alternatively there're the chans where there's always someone who knows a thing more than anyone. Though, there're high chances that someone here already had to deal with the ofs3 format in the past and could contribute to the discussion.