I don't understand why anyone would bother doing something like Stow. I keep my home directory directly in a Git repository that ignores all files by default, and for systems with specific configurations, I simply create a branch.
Wasm has a fundamental problem: int64 is an insufficient data type for real use cases. If you want to create some kind of plugin system based on Wasm, you need to exchange structured data. But most languages disagree about the memory layout. Dynamic languages do tagging, compiled languages do not. And the UTF issue shows that even with strings, there's still no real agreement.
Furthermore, there are now competing interest groups within the Wasm camp. Wasm originally launched as a web standard: an extension of the JavaScript environment. However, some now want to use Wasm as the basis for replacing containers: an extension of a POSIX environment.
The data exchange between host and guest is still unspecified. You can not access host objects from Wasm. Most do just string serialization, which is not fast. Or they write libraries for some particular languages, which damages the universal idea of Wasm. And WASI seems to be quite controversial: https://www.assemblyscript.org/standards-objections.html
I think the XDG spec is pretty petty. What difference does it make that the files are in ~/.config/mozilla instead of ~/.mozilla? And calling it a bug is presumptuous.