when you said "I tried fitting super smash bros (16GB file) and worked", what do you mean exactly ? you have put the game,
then checked its hashes (SHA1, MD5) to make sure it's good ? You can put anything you want on a fake card...except that at the moment where you exceed the real size of the storage, you will start to overwrite the file(s), and corrupt it, one by one (and OS will report everything is good, because it can't detect fake cards...if the declared size is 512GB, it thinks it can write 512GB, as simple as that).
ps : the brand of the microSD card does not matter at all...everything can be copied, cloned, imitated.
You must check it with h2testw. fitting a lot of games is NOT a way to test it, except if you check EVERY HASH of every file you put in it (exactly what h2testw does...automatically)...but if you want to lose your time, do it yourself, no problem