I saw that there’s this nifty xdg-ninja that informs you on what you have installed that doesn’t respect the XDG spec, if it has support for it or not and what you can do to make it comply.
But now I was wondering if there was any tool to do the actual work automatically, I believe I have once seen a program that spoofed your home directory to non-complying apps so that you could transparently override their whole app data location to a path you wanted so they can keep functioning, but I can’t for the life of me find it again.
It would be double awesome if it did both, i.e. auto-applying any changes to apps that support XDG but need to be configured to enable it and, for those who don’t, forcefully spoofing the home directory