This file has not been tracked for years. Nobody added when new features
were added, when existing code was broken, etc. E.g. none of the changes
since EWMH 1.4 is listed, none of the kde specific extensions is listed.

The document does not contain anything about Wayland protocol support.

I would not trust this document at all to say whether KWin is compliant,
but would check the source code. And after all most of the compliance is
done in KWindowSystem and KWayland, not in KWin.

Also the document lists compliance of other non-KWin elements such as
Qt, kicker (kde 3 thing, not application launcher), etc. This shows it's
also something which doesn't belong in KWin's source tree.