I tried turning on the tagging Addon and found that tags can only be applied to the initial discussion. Can it be enabled for tagging comments as well?
No and I didn’t think it would be that good, it would likely produce more noise information.
That value of tagging is it relates things. As comments belong on a discussion list rather then out of context, this will likely appear a bad link farm to a search engine.
You would expect a lesser quality of tag, and you are compounding the problem, becuase that will relate to content of a lesser degree of relevance both comments and discussions.
It is hard to get relevance at scale, it is something that is gradual built up, and you throwing into he mix both discussion an comments.
Relevance is key an on a forum, relevance is related to the comment in context of the discussion outside of that is is mostly noise, interconnecting doesn’t necessarily have much benefit.
grep is your friend.