I didn’t read the whole article, just a cursory glance really, but it seems like that is the exact other way around that I would want it.

I’m thinking of scanning a paper bill with my phone, extracting the text and matching parts of the text to firefly fields, like transaction description, source account, destination account, amount and maybe categories/tags.

I have Firefly III and am really quiet happy with it. I might write a companion program to scan bill though, since doing everything by hand is rather time consuming.