The autonym font was developed in 2012 to avoid tofus in language name rendering in wiki pages. At that time, there were old operating systems and browsers in usem especially windows XP with less support for languages than Wikipedia has. It was never meant for a long term usage. 4 years later, there is better support for scripts in operating systems, new fonts were developed and are available for users. Language team has decided to gradually reduce its usage and finally retire autonym font. The upstream development for the font has stopped years back and there is no plan or resources to maintain it.
Every new version of operating system adds more rendering capacity and bundles more fonts. See
https://en.wikipedia.org/wiki/List_of_typefaces_included_with_Microsoft_Windows how fonts included changes in every version. For rendering, Universal shaping engine by Microsoft and Harfbuzz are keeping up to support more and more language tags defined as part of Opentype spec