I can't speak for changing skin tone, since I don't edit it,
but I definitely can speak for fashion block editing.
I literally just imported it, and checked the clothing, and they are indeed there.
edit: I just changed by skin tone via block editing, and it indeed changed.
I'm under the impression you're doing something wrong, hence neither the fashion block edit or skin tone edit are showing up for you. /edit
Try to only import the fashion block, and see if the change it there.
Then export the save with PKHeX, and import the save into your game with a save manager.
If not, you're clearly doing something wrong.
If that worked, now try to do the same steps, except now with skin tone changing. Just change one for now.
See if that works.