It's not, my DS is also on 11.5 and SaltySd works just fine.... I don't know what you guys are doing with your edits/patching/file placement but everything does work 100% on Luma v8.1 and 11.5. I've never tried using Luma's LayeredFS, but the other options work for me. Not only does SaltySD work for my texture edits, but also QR injection patches, no outlines, PC Anywhere and NFC patches.
I'm not sure why some people have issues rebuilding the structure after. I've had to walk more than a few people through it in PMs or even rebuild the CIA for them myself with their edits to prove it was a user error and not the program/console.......