Sorry about your frustrations. I ended up aligning a lot of my metadata exactly with allmusic as well until I gave up as an impossible task. Many here have had the same experience. I have had some success with songkong, as have others in these scenarios. It automatically retrieves roon friendly metadata so you don’t have to make the changes manually. My own experience is that it is a bit hit and miss, but it is worth a try rather than not doing anything and having a messy, ugly roon.
These days I only do the editing when I notice a problem (and can be bothered), rather than trying to be systematic about it. Unfortunately, in many genres, especially classical, we are many, many years away from correct, bullet proof and interchangeable meta-data where significant manual editing will not be necessary. Roon does a better job of that than anything else I know but it is far from perfect in several genres.