I'll be completely honest. I like the concept behind the level being shared across saves.
It's a good idea to kind of give a "consequence" for losing to temptation. Something that is clearly missing in GoR games in general.
The whole idea of Level Drain is often misused by devs, because you can simply load to remove that consequence, so it's a good answer to that "Lose on purpose => Watch the Scene => Reload => Win" loop that plague the whole genre.
The whole game being balanced at around level 30 help a lot with that, too. After all, if you have too many levels, you have more incentive to give them up.
While I'm talking about giving up levels, getting Level Drained by your allies isn't a problem either, as it's supposed to give you other permanent rewards which ends up making you stronger overall, thanks to the SP points.
Personally, I would also give the player some sort of reward once Trust 100 is reached, like upgraded versions of Richard's basic skills, for example (Kage Onna could give an improved version of the Will restoration skill for example).
Now. Does it have problems? Yeah, definitely. But grinding itself isn't bad. The real problem is what is the grind. It's just annoying to fight random monsters in a turn-based RPG Maker game just for the sake of it. Especially with how those encounter works (going to a dungeon, then running around to find encounter spots), and even more so when most of those enemies are very weak anyway. The whole first-person dungeon crawling mechanic is pretty badly made overall, too.