For Warpless, NTSC-J runs exactly like NTSC-U but you'll lose a lot of time to cutscenes. This basically sums up the differences: https://pastebin.com/gmHM9f3v

Also obviously no language glitch on the J version.

If you're interested in TTs, Penta Penguin has max stats on the J version like the PAL version.

japanese version is not good for any of the crash games in terms of speedrunning, at least from the ones I've played

The Japenese version of CTR is faster on some Time Trials just because Penta doesn't have max stats on the NTSC-U version, but does on the J version. It's just not so good for full game speedruns.

As for PS1 Crash games, it's a little off topic but Crash 1 100% is the only category that's faster on J