Xlibre is backed for the most part by the singular maintainer that was still willing to work on X11 who got kicked out for being too toxic and breaking existing code. For what it's worth, it also explicitly used MAGA language in its README for a while.

Phoenix is intended to allow for support of legacy software/DEs and provide a more modern/maintainable version of X11. It isn't trying to compete with Wayland, it's trying to live alongside it for environments that won't or can't move to Wayland. It also technically won't be a complete X11 implementation, as it's ignoring older portions of the protocol.

Neither option addresses the elephant in the room: The X11 protocol is still fundamentally broken in a lot of aspects. Multi-monitor support, especially when monitors aren't the same resolution, refresh rate, or physical size, is broken at a fundamental level. It will never work even as well as Windows, which is already an incredibly low bar to clear.

Wayland is slow moving, sure, but it is a much more stable base to work with than Xorg ever was. From a security, modularity, and extensibility standpoint, Wayland is a lot better. There is a reason most of the Xorg team developed a completely new protocol instead of just reimplementing X11 themselves.