I wouldn't trust a fake SD card even with a "correct" partition. From personal experience accidentally buying a fake 256 GB card and correcting the stated partition as 3.70 GB, I still have files corrupt and delete themselves. It sucks because I had a lot of VC games that went doh-doh because of that card, so please. Do yourself the favor and saving a headache. Go get a real card. 32 GB micro SD, dunno how France does it. Try price matching amazon.fr against in stores.It definitely is ce on my 2ds, all my 300+ themes were gone after deleting it.
And fake or not, it still is a micro sd i guess. i'll fill it to get its real capacity and shrink the partition (i'm expecting around 64gb). I may also try the guide tomorrow, and get you informed if anything interesting comes up. Thanks for the help =)