Work required on AboriginalSerif font collection
The PDF dictionary uses the Aboriginal Serif font, which lacks the characters subscript one (U+2081, ₁) and subscript 2 (U+2082, ₂). These are needed for some morpheme identifiers. I used FontForge to construct those characters based on the superscript versions, U+00B9 and U+00B2 respectively, in each of the four font variants (regular, bold, italic, bolditalic), and the results seem to be OK. This is worth recording because it means that the font used in the project is customized and therefore you can’t just swap it out for the default AboriginalSerif.