Facebook has now upgraded the test of its up and downvotes for group comments with new badges that can be used to display the commenter why you find their comment valuable.
Recommendation:
Facebook Announces New Messenger Branding & Releases New Messaging Features
As you can see in the above image, with the new up and downvote option is made available in your group, you will get to see a prompt that notifies you to the option. Facebook has also added another explainer screen to the alert.
As seen above, Facebook is also working on some new icons that you can use to add to comments which will further be shared with the author.
Facebook back in 2018 tested the option for general comments on posts not just in the groups but in a set of different formats.
This test came to an end after a few weeks but Facebook does seem to see value in voting as a form of comment moderation and making sure the most engaging comments get attention.
Conclusion
This seems to be a valid addition to the groups. Facebook has not given any insights on the test yet, but it is clearly working on it. It is an interesting option to look for once it comes out.