Saving a create block with a facade on it into a structure block doesn't save the facade, so it functionally can't be used for structures of any kind

Placing a structure you've saved with a facade on it just causes the create block to be placed as normal, but with no facade on it

Do you have ant idea how i would implement that ?

I haven't looked at the implementation of the mod much, but assuming you're using WSD, you could potentially jump in on where the structure NBT files get saved, add your own little block that links blockpositions to facade data, then re-create that in place when the structure is placed