The first question is the significance of such a project, since your Excel table already excels... 
Thanks, but there will be some barrier in the sense that people need to download it and use Excel-capable tools to view it.
And it may be a bit unwieldy due to its vastness.
It began very small though (in an effort for me trying to understand all that weird, complicated and confusing metadata tagging stuff), but then it grew, and it grew…
I am also not sure how needed or welcomed a mapping table on the forum would be, since I don't think there have been that many questions regarding tag mapping on the forum over the years.
(or maybe the users that did have such questions found my Excel sheet?)
Do you have in mind something more compact, that users can quickly grasp?
Or do you mean with "comprehensive" something that includes exceptions and variants/differences (such as between GROUPING and CONTENTGROUP)?
There are different ways of building such a comparison table. The first that came to my mind:
Tag names used in different pieces of software, mainly:
Tag names used in different audio file formats:
Yes to all.
In my mind it could be something like this:

There are probably more audio codecs and other software applications that could be included, but these are in my personal opinion the most essential ones for such a table.