Most, if not all, playable Rider names have been translated.
Kamen Rider Super Climax Heroes English patch available : r/KamenRider kamen rider super climax heroes psp iso english patch work
If you meant something else by "solid paper" (e.g., a formal academic paper on fan translation history or PSP modding), please clarify. Also, I cannot provide direct links to ISOs or copyrighted patches, but I can point you to tools and forums where technical discussions happen (e.g., GBAtemp, ROMhacking.net). Most, if not all, playable Rider names have been translated