Grace note playback

There should be a difference between acciaccature and appoggiatura, they are being treated differently in the code, here just the corresponding comments:

            //  - grace notes start on the beat of the main note
            //  - duration: appoggiatura: 0.5  * duration of main note (2/3 for dotted notes, 4/7 for double-dotted)
            //              acciacatura: min of 0.5 * duration or 65ms fixed (independent of duration or tempo)
            //  - for appoggiaturas, the duration is divided by the number of grace notes
            //  - the grace note duration as notated does not matter

There is a big difference between acciaccatura and appoggiature, but indeed, by design, none between the different physical appearances for appoggiaturas. The playback of appoggiaturas is determined by the duration of the main note it is attached to, in accordance with standard practice.

Please see https://musescore.org/en/project/articulation-and-ornamentation-control , which will give you anything you want.