See How is it possible that a single user who is not a moderator can delete a comment? for more details.
In short, two comments have been probably deleted after a single user flagged them as obsolete because they contained accept or accepting in a sentence.
I found out that, as moderator, I cannot undelete those comments for which the deletion threshold is lowered to 1 flag.
Since on Drupal Answers users could ask a question about a module for accepting answers, the word accept could be contained in a comment, even though the comment is not saying anything about the user not accepting answers given to his questions. For example, the comment could be "What is your module supposed to do when you accept your own answer?" or "You can accept your own answer, and the module doesn't consider that possibility!"
In that case, a single user who flags the comment as obsolete would cause the deletion of the comment, even if the comment is not obsolete at all. As moderator, I cannot do anything to reverse that.
Moderators should be able to undelete those comments for which the system decides they can be deleted after being flagged from a single user.