Hi Robz I would like to give you an update, hope its helpful:
I got Final Fantasy Tactics A2 to work with the nightly you provided:
In the per-game settings besides changing the release to nighty I also changed the clock speed to 133hz, boom it works perfectly.
I tested all other combinations on and off but this is the one that makes it boot, with this on you can have VRAM on or off etc it doesn't matter. One thing that happens with Final Fantasy and few other games I've noticed while testing is the bootstrap menu is black but it still works, i.e. press down a few times and A and it will quit the game or press up and A and it resumes, also visual glitches in a couple of games, one has like a white pixel static on the bootstrap screen like the matrix but scrolling horizontally. I was testing other stuff but if I come across that again I'll make sure to note it but at least on my DSi FFA2 consistently shows the black screen there.
After that, I tried it all on the other game with the same white screen issue: Spider-Man Edge of Time but no luck.
Also, I suspect the games I reported have different issues, so just to make it clear:
FFA2 and Spider = White Screen
Top Spin 3 and DrugWars = Black Screen
Anyways, thanks and cheers for all the work!
edit: somehow after posting this I've tried the bootstrap menu in FFA2 but in a battle scene instead of menus and It showed the options just fine so yeah, it seems consistent on the intro credits and menu, if that's helpul.