Auto stem direction for between-note/two-note tremolos incorrect

If you add a "between-notes" tremolo (fingered tremolo/two-note tremolo) between a note just below the middle staff-line and one on the middle staff-line, it still tries to keep the stem direction down for the second note, resulting in wonky looking tremolo beams. In fact I don't think stem directions should ever be different between two notes in the same between-note tremolo (at least, not using "auto" stem direction, see Gould "Behind Bars", p 226).
This is even a problem for whole notes either side of the center staff line and worse, the tremolo is incorrectly horizontally centered if you "flip" one of the whole notes to cause the tremolo beams to be drawn above (or below) both notes.
This looks to have been reported before and "Fixed": https://musescore.org/en/node/29686 but the current behaviour is definitely not nice (if you take the attached score there and set all the stem directions to "auto" you can see the issue in various places)
I also noticed that tremolo beams often draw through accidentals, which has been reported before but still unfixed.
Relatively minor issue at this stage at it can be worked around by flipping and/or manually repositioning tremolo beams.