Combine Fretboard diagrams and chord symbols
From a UX perspective, adding, copying, and positioning both fretboard diagrams and chord symbols is clumsy and error prone. Since the fretboard diagram defines a chord, it would be better to optionally display the chord symbol as a feature of the diagram rather than as a completely separate item to insert and manually position. This would allow default alignment and when moved or copied/pasted they could be done together.
Internally, the Harmony element in MusicXML supports descriptions of fretboard diagrams, though MuseScore does not currently appear to use this feature. Using Harmony to describe and manage fretboard diagrams would simplify the implementation of the described above.