I think you’ll find a whole country of Icelanders who do not consider the ð to be a “niche” glyph. And I imagine many Eastern European type designers might make the “niche” glyph complaint about that… (View Post)
As John implied, the alternative discretionary ligatures will need to be made accessible through a combination of features — i.e., to get an alternative discretionary ligature, both {dlig} and {ss##}… (View Post)
{aalt} cannot take ligature substitutions. So the warning is appropriate, but can just be ignored. Or remove ss01 from the definition of {aalt}. (View Post)