I had @lifehackerhansol take a look on Discord and they were able to replicate the same results. There seems to be something around with the autoboot launcher for the DSTWO that's causing the issue.Clean and trimmed don't matter. Also, B4DS mode worked fine on DSTWO, last time I tried. Not all games will work, ofc.
Also, weird that they aren't working with nds-bootstrap turned off either. I'd say your ROMs are corrupt, but considering that they work on DSTT just fine, I'm out of ideas.
That's normal. Proper soft-reset isn't implemented in B4DS mode.
Worth noting that these are my own ROMs that I dumped from the games to test them, but I did replicate with a ROM that I grabbed off a ROM site to compare results. I know the ROMs are not corrupted.