@Artiarna
You keep calling it DSTT instead of TTDS.
Is your card labeled like so? If so, it might be a clone card, which is why you can't see your roms.
That's a possibility.
The other one, "newer" DS games has antipiracy measures that might be causing them to not appear. Also, some flashcards must be
flashed against such security measures... in some cases the appropriate patch must be added to the rom itself.
Third possibility, depending on how bad of a clone your card might be, it won't accept original kernels. There's been cases of TTDS cards getting bricked by the kernel if it detects it's a clone. That was in 2008/2009 though, not sure how modern this stuff is nowadays... and I've been out of the DS Flashcards scene for almost a decade now.
But anyway, if your card is a clone TTDS, use Wood Kernel which is made to add compatibility with clone flashcards.
EDIT:
Fourth possibility, your roms might be badly dumped. Try downloading from another site!