All look fine with Segoe UI Historic, however.

Can you suggest how to reformulate the rule? My intent was to pass
every whole akṣara to the shaper.

>>  ("a" ["𐨀"]) ("i" ["𐨀𐨁"]) ("u" ["𐨀𐨂"]) ("R" ["𐨀𐨃"]) ("e" ["𐨀𐨅"]) ("o" ["𐨀𐨆"])
>
> Can you please reformat this to have just one rule per line?

Okay, done. Please find new versions of both files attached.

> Would you be willing to start the legal paperwork of the
> copyright assignment at this time? If yes, I will send you the
> form to fill and the instructions to email the form.

I was dreading that process, but am willing. Yes, please send me
the forms.

Many thanks for your quick response and help!