Here's the encoding vector (one needs to add it to at least
enco-ini.mkii and font-enc.lua, maybe to typescripts as well, though
not necessary if you don't plan to use mkii).

It's not too well tested and I also wasn't able to decrypt what all
the characters in encoding are.

(In particular case mappings for german double s and dotless i might be wrong.)

Then you can use encoding=l7x in lang-bal.tex. It seems to work for
me, though I have no idea if it also works properly.

Mojca