Here's how I do commendations:

1) if somone is chatting or spamming emotes during the run then they'll get it.

2) if it was a silent run then i'd give it to the first player saying "gj guys ^^" or something like that at the end of the run.

3) if non of the above applies then I'll commend somone if they played noticeably better than the rest.

It could be a wrong approach to using commendations but that's how I do it.