Aha, it's Thabeast721:
https://www.youtube.com/@Thabeast721/videos
I'm also aware of N64 Glenn Plant's reviews, but as far as I know he's only committed to doing the NA and PAL libraries, with a smattering of Japanese games as he sees fit (he's done 23 of 85).
As for the feasibility of doing the Japanese part of the library too, I'd agree that odds are against succeeding within 1 year. Maybe half are either playable without Japanese or have a translation patch (~20 Japanese retail games have been fan-translated). And we'd have to work through baseball games, shogi games, horse racing games, etc.
Still, it'd be fun, and the N64 has the most manageable Japanese-exclusive library of all major consoles except maybe the XBox. Well, the Master System JPN-only library is small too, but the European and Brazilian libraries sure aren't.