The canned review comments already change based on the reputation of the post owner. A couple of the comments could be improved if they also factored in the case where the comment is being left on an answer posted by the question asker:
This is commentary on another post, not an answer
This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient reputation you will be able to comment on any post.
This wording is awkward in any case, but the part about "requesting clarification from an author" makes little sense when you're commenting on your own question; most of the time these answers are question updates. It should probably just say "you can comment on any answer on this page", without any mention of rep since it doesn't matter for askers, and also mention something about editing the question to clarify things instead of posting edits as answers.
If possible, it might even be nice to split this into two cases and have a new "This is an edit to the question" option, since it's such a different situation from somebody leaving a comment via answer.
This is a “thank you” comment
Please don't add "thank you" as an answer. Once you have sufficient reputation, you will be able to vote up questions and answers that you found helpful.
Before talking about the upvoting they can't do anyway, it should tell them about accepting an answer, since the question is apparently solved and they're the only one who can mark it.