I don’t have any blwm in there yet. Just an auto-generated abvswhich I don’t need (the glyphs are not drawn yet)
script khmr;
lookup Abvs1_khmer {
sub iMark-khmer toandakhiat-khmer by iMark_toandakhiat-khmer;
} Abvs1_khmer;
I took out the script khmr; anyway, but that doesn’t change anything.
The glyphs files are very rudimentary yet, so I can imagine some mistakes on my side. But the setup with anchors in some base glyphs and first level marks should reveal some working anchor attachment already. Hmmmm.