I work on dubbing a lot of shows and, from my perspective, non-language vocalisations are more than welcome in the M+E. However, like everything in life, it depends on specifics. Here's a list of things that come to mind:
Specific non-voiced mouth sounds like kisses are often done by foley artists anyway, so there's no reason to omit them from the M+E.
If there are characters who never say actual words, but maybe grunt or laugh, it feels like a waste of time to dub them.
Walla should always be included in the M+E.
Breaths and nose whistles are borderline because they may sound slightly off if the dubbing actor is miked differently, or has a different timbre or pitch.
I love it when mixers think ahead and save me time, but some clients might have weird M+E specs, or an overeager QC engineer might reject an M+E for having mouth noises. The best solution for this i've encountered is an "options" track. It's just a mono track that includes any borderline non-verbal vocalisations, such as those i mentioned above (except for walla, which should always be FX). With this, you can output a QC-safe M+E, plus a separate track that will really help out people like me.
Thanks for asking the question! And thanks to any mixers out there who take the little bit of extra time to create a comprehensive M+E.