Well, regardless of how it “ought” to work (or not) this is what it looks like in SumatraPDF.
That looks like “bold, normal, and italic” in the document to me. And I don’t have any version of the Aviano font on my PC.
If Adobe reader wants to complain about a missing font, that’s OK - so long as it produces a meaningful message, not the garbage it actually produced.
Internally the PDF refers to Aviano Sans Regular and Aviano Bold (and also the Dorico supplied fonts Academico and Bravura). On SumatraPDF both versions of Aviano display correctly (compared with samples from font downloading sites) so they must both be embedded in the document.
I’m not convinced the Adobe Reader problem is related to fonts. I can’t see any evidence either for or against that idea.
