I think you should either try to find way to translate Wayland coordinate space to Wine coordinate space, or maybe not worry about where the windows actually are in Wayland space. Also, unless this MR is a hard requirement for the rest of the driver, I think you can perhaps try opening merge requests for other more independent parts of the driver, in order for it not to be blocked until we have a better solution here
I think not syncing the windows would be fine for now, but ideally I would like to have some solution for the input clipping issue (see other comment) since it's very annoying and confusing for users (me included!).
Performing some rough tracking and moving of windows to the right monitor, based on the Wayland output they are on (point (4b) in the MR description) will help with proper multi-monitor integration (e.g., the compositor deciding to make a surface fullscreen on a particular output, and we want to reflect this on the Wine side, too). I think that this would be less problematic since we could at least try to make it be a one-off request, rather than a persistent forceful move. In any case, let's leave that for later.
Practically, this all means that I can just drop the last commit from this MR, and perhaps move it to a parallel MR where we can continue to discuss solutions, while we move forward with other things. The rest of this MR doesn't really depend on the last commit, so it would be fine to move forward without it.
I believe we would be very happy to have even a roughly usable driver for 9.0 (in two month time, if that's reasonable for you ofc).
That would be ideal and is my (best-effort) goal, but I don't expect we will be able to reach full feature parity with the experimental branch in this time frame. I will need to prioritize the features which maximize "usability" for some particular target. For example, if the target is primarily games, then I would need to ensure we get in mode change emulation, GL/Vulkan, basic keyboard, and relative motion. I would deprioritize features like copy/paste, full keymap support, cross-process rendering (although that would help with some games/launchers/store apps, but is unfortunately quite complex).