Add the oud as instrument
Following this thread (and the recent last comment), https://musescore.org/en/node/139241, I believe it would be appropriate to add the oud to the list of instruments.
Of course, the large number of possible tunings (more than a dozen) and, as a corollary, the lack of a standardized tuning, is a constraint.
Nevertheless, this is not, should not be a sufficient reason to deprive this instrument, played anywhere in the world, of any display in MuseScore.
To each one, then, to personalize the tuning, according to its instrument ; but at least, there will be a visibility, an important starting point.
I looked at several sources.
This source: https://en.wikipedia.org/wiki/Stringed_instrument_tunings#O which indicates that the most common tuning is: C2/F2/A2/D3/G3/C4
This one: http://www.atlasofpluckedinstruments.com/middle_east.htm : D2/G2/A2/D3/G3/C4
And the third : ditto: http://www.stringedinstrumentdatabase.comoj.com/n.htm
On the Spanish wiki page: https://es.wikipedia.org/wiki/La%C3%BAd_%C3%A1rabe, the first one is mentioned as the most common.
On the Frenck wiki page: https://fr.wikipedia.org/wiki/Oud, it’s the second one !
And on the English wiki page: https://en.wikipedia.org/wiki/Oud this point is not mentioned.
At least, we can observe a common point for the four first strings (bass to treble : A2/D3/G3/C4.
Not an absolute rule, but a good start.
So, for the two other strings, at one point, we have to put an end to the debate, and choose.
I propose the first one, ie: C2/F2/A2/D3/G3/C4
(for the reason that I observe in the dozen and more tunings as I mentioned above: often the top string and the lower string have the same note, eg: C2/C4. Again not a rule – mine is different!- but a bit more observed)
On Sibelius (7.5), it’s another thing/choice (in fact : it's one among some other Turkish tunings), but the top string and the lower string are the same (two D).