Read first post again try 8250-8400 WM Aero Re-Enabler registry trick for aero. If dism not allows to install at betas try first post registry keys and copying your files. As the files are a few, maybe mum and manifests can be edited for beta versions number and cat can be recreated.
Main thread/post updated with: [Update from March 22, 2025] - Related to Windows 2008 R2 specific procedure; and [Update from March 22, 2025] - Added images for Windows 8.1 and Server 2012 R2
I did not try something like this before. But I'm planning in two different versions. Timebombed version (by taking files from 7000, replace versions in .manifest and .mum files, re-generate catalog) Debombed version which is way tougher. But thanks, I ran out of ideas to do anyways.