Hi there, I have not tried that, but not sure if that is possible. This is a document version report and it definitely doesn't pull that in, but I tried a document report just now and not seeing a way there either.
I'd ask though, even if you were able to pull in # of comments on a proof, that wouldn't necessarily correlate with # of changes or even the scope of the comments since some comments may be along the lines of 'looks great!' or some may be questions from the proof owner to clarify proof comments, etc. Pulling # of comments could be misleading in whatever you're trying to glean from that.
If this helped you, please mark correct to help others : )