I'm hitting a problem with FreeType / HarfBuzz / Cairo interaction for variable fonts that is easiest solved in FreeType. Currently, if one sets Blend coordinates, then gets Design coordinates, the returned design coordinates do not reflect the set blend coordinates. Can you please fix this? Ie. work backward form blend to design coords (reverse of avar and normalization) on demand?
Also something to keep in mind re FT_Set/Get_MM_Weight_Vector(), but maybe not since that's Type 1 only.