No, there is no compatibility list out there, i am sorry.
The reason is that we are not parsing the recipes literally but use a standard that many sites stick to. If a site provider changes their (invisible) metadata, the import might suddenly work out fail:
Often, the standard is not adhered to by 100% and minor flaws are compensated by the cookbook app. Typically they check if Google’s rich text engine understands their data. If yes, they are satisfied.
This also means that each URL not the domain could be compatible or not. It would be more fine grained. The data that is parsed is just some sort of invisible “comment” within the HTML source code.
Does this make sense to you and answer your question?