This is because SKELUX broke the rom's FNT by replacing the first four bytes of it with HACK (0x4841434B), which makes it impossible to open in every DS game editor.
The offset to the FNT can be found at 0x40 in the rom's header. It is four bytes long.
Additionally, the first 16 bytes of the rom's header have been modified. This has the effect of making the rom unopenable in SM64DSe because SM64DSe checks if a rom is SM64DS by checking the header. Finding a better way to check would fix this.
I don't think it's worth it to add a check just for one hack. It seems to be better to directly use the total directory count in the FNT to obtain the table offset.
This is because SKELUX broke the rom's FNT by replacing the first four bytes of it with HACK (0x4841434B), which makes it impossible to open in every DS game editor. The offset to the FNT can be found at 0x40 in the rom's header. It is four bytes long.
Additionally, the first 16 bytes of the rom's header have been modified. This has the effect of making the rom unopenable in SM64DSe because SM64DSe checks if a rom is SM64DS by checking the header. Finding a better way to check would fix this.