That game is maybe like Mario Kart double dash...
DIOS MIOS is not emulating the memory card, it only redirect the save file to be written to SD or USB instead of beeing written into a "virtual memory card file".
The virtual memory card file can contains any binary data, filename, etc.
But on SD or USB, only FAT32 characters are allowed and some games are using random non-ascii letters for their save's filename.
when DIOS MIOS see that you want to write the save file to SD it replaces the incompatible characters in its filename with spaces (or underscore, or just discard them, I don't remember) and the file is saved.
but when the game try to open the file, it can't find it as the expected filename is different.
I recommend using Nintendont instead, which is not saving savefiles directly to SD/USB but are using an emulated memory card file.
Memcard.raw <-- inside you have blocs and it can store multiple games, etc. just like a real card.
Nintendont doesn't need MIOS replacement, and don't care if you installed a different MIOS.
it will not conflict. You can have both DIOS MIOS and Nintendont at the same time.
see the first post of nintendont thread (in the vWii section) to see how to install and setup.