Part of the motivations for this backplate were lower soc temperature and that it resolved the wifi problems (see Solving heat related issues with custom lid).
At that time nobody knew what caused the problem with the wifi, now it is known and you can buy a new backplate directly from mnt that solves this (I replaced mine last week and it is night and day).
I suspect with the wifi thing solved there is less interest in this project. I am not saying it stalled because I am not behind this thread’s backplate, but I suspect that interest is lower than when the thread started.