Use the tools provided in the nzxth2 tf6-translation repository to "repack" the English text into your original ISO.
With Master Duel and Legacy of the Duelist available, why bother with a decade-old PSP fan translation?
This is the most popular method. The PPSSPP emulator runs on Windows, Android, iOS, and macOS. It allows you to upscale the graphics to HD resolutions.
Initial patches focused primarily on card text to make the game playable in duels, with story translation following years later. 3. Technical Implementation and Compatibility