Tuplet numbers don't use the Musical Text Font, but FreeSerif/Edwin
When selecting Bravura to be used as the font for the tuplet numbers, MuseScore doesn't use the symbols provided by the font. I've attached a screenshot showcasing the tuplet symbol manually dragged from the master palette (below), vs. what I actually get (above).
OS: Windows 10 x64
MuseScore versions tested: 3.0.0, revision: ef48b60, 2.3.2, revision: 4592407