Yeah, most lists in menus have been fixed over the years- but certain ones still only show sharps. Still, notes are spelled correctly in the Key and Score Editor. Note that the Score Editor has its own pref in Score Settings>Project>Accidentals
Insert a chord onto the chord track, and leave it undefined: ‘X’.
With that chord selected, observe the “root key” field in the info-line. It displays the correct enharmonic spellings, including mixing flats and sharps in the same key.
So use this menu instead of the scale menu, it fulfills the same function.
btw, though the note D# is the same as Eb on a piano keyboard, “D# major” is an impossibility since it would have to include
two double sharps for a total of 9 sharps!