be sure your SD card is formated to FAT32 with 32k/clusters.
I know users are recommending 64k/cluster to speed the load time in some games, but it can cause issues in few games (like mario kart 8)
Also, playing a Game from a different region might require folder name, filename or even file's data edition.
The game is looking for folders named after your own region and language.
for example :
You want to play a EUR game on your USA console, in english.
look for folders named "EUen" (for EUR region and ENglish language) and rename it to USen (for USA region, ENglish language)
Some games need edition, while others don't.
To know which file or folder needs to be renamed, you need to enable the log Server and watch the accessed files.
If a file is requested but can't be found, you will get the expected path. rename the other language's folder or file to that name and try again.