

I couldn’t find the specific reasoning for this change, but I feel like QEMU is probably just too holistic to be appropriate for this kind of project.
QEMU needs to be able to emulate all the ARM hardware with enough fidelity to boot a naive operating system. For the purposes of running userspace applications almost all of that is not required, you really just need to convert one ABI to the other and translate the instructions. No need to handle firmware, the MMU, interrupts, disks etc.
Yes. It has basically the same issue that any compatibility layer is going to have. It will either faithfully reproduce X11 so well it will bring all of the nonsense Wayland was meant to do a way with (everything not directly related to displaying graphics, like font and geometry rendering from the '80s, network transparency, insecure event handling) OR it will attempt to get a reasonable subset working for modern X apps and it won’t be compatible with dusty old binaries and X forwarding etc.
Right now it looks like a shim for Xwayland so it’s the first one, but as it matures we’ll see.