The example for replacing Arabic numerals by Indic digits inside math used to work (at least) until version 2017.01.17 17:37.

tex/texmf-context/tex/context/fonts/mkiv/type-imp-mathdigits.mkiv

Now in version 2017.04.27 01:00, this does not produce the desired output: it's all "Latin" digits.

Has something changed regarding fontfallback definitions?

Thanks,

MHB