As part of my usual rechecking of games when too much of my system changes, I retried this game, and it now finally works (previously it just crashed on startup). It's not perfect (a bit slow - especially the in-engine unskippable cutscenes - and occasional graphic glitches, such as red splotches in opening anim, and totally random graphics in tutorial battles), but I was able to play for a few hours without problems. This was with wine-2.12-staging, amdgpu hardware with mesa-17.1.5, clean wineprefix (no winetricks). The loader doesn't work right, even if you use wine's mono (wine's mono allows it to start, but it crashes if I try to edit options). To edit options, manually edit config/Grandia2_Settings.ini. Mono/.NET is not needed for the main game (grandia2.exe).
I think I'd still recommend just playing the original on a Dreamcast emulator, though, if you can find one that isn't broken.