Custom timing on Grace notes and Mordents?

I need to find a way to customize the playback timing of grace notes and inverted mordents.

Relative to my violin and fiddle experience MuseScore's grace note playback seem prolonged, having an early onset and overly sustained duration.) I'm not criticizing the default. Just need to customize it if students are to play along and use Musescore's playback as a model.

And the inverse mordent is often used to represent the the short roll or long roll in Celtic fiddling. But the default timing sounds like a reasonable succession of literal notes, whereas the intent in Celtic fiddling is to sound a swung cluster of two grace notes. And I'd like to stick with the traditional fiddling nomenclature rather than writing two grace notes—there are many advantages to doing so.

Are either of those goals attainable in MuseScore—ideally as a style I can apply "per score" or as a style I can apply per ornament? If so I'd love to know how.

If not, please consider this a request.

Thanks for any feedback or advice on this!

scorster