TeamMood exists to make issues appear, and we understand that it could hurts when someone posts a negative comment.
The first thing to know is that it usually reflects a behaviour that's already on the workplace.
The best way to fix it is to address the issue at the team level, by sharing the issue and to ask teammates what they think about the comment, and what could be done to mitigate the issue.
Here are some proposals for you:
on TeamMood, reply to the comment by asking the author to get back to you for discussing the matter privately.
at the workplace, ask people to respect the TeamMood's code of conduct, and if they want to post negative comments, at the very least, ask them to post it with constructive criticism, eg sharing a proposal so that the issue could be fixed.
if you cannot address the issue, because it's outside of your area of influence, just tell the team that you cannot fix the issue, and that you can only share it at the upper ladder.
If the comment breaks our code of conduct, please check our moderation policy to address the issue.
In any case, feel free to contact us if you need any advice from us.