As I understand it, the issue isn’t really generating the required glyphs, it’s having a place to put them so that others can access them in a standardized way.
Creating the glyphs and adding them to a Private Use Area (here I used 0xe100 and up) is easy enough: select, duplicate, rename, scale, align, engorgio —and you’ve got another hundred or so superscript and subscript characters in your font:
Perhaps 50% scaling was a bit too aggresive… 
I’m assuming that the (simpler) proposal is to get standardized Unicode values for these. Making the required glyphs isn’t an issue.