I have never dealt with Logitech, but I wouldn't expect that approach would work at all. The two *.hex files contain device numbers and function numbers, without any indication of the actual function that they are supposed to perform.
Maybe if you made one file that excised the unused functions, and included the function name next to each function number, perhaps they would work with that.

I guess you should include only a few functions that already work, clearly marked as already working. In that way, they don't need to sort through much, but would have some confidence that the code are correct if the already functioning codes match their database. Have you thought about which keys they should map the functions to? Is there a straightforward way to do that, and one that other users would find intuitive? If not, they may not be too responsive in setting this up--it's not clear how populating obscure functions helps their bottom line.

Frankly, if Logitech were really interested in populating their database, they would accept just a device number and function number, and not require Pronto Hex.