After some further research, I conclude that the "ROM-SAL" is simply the Rawlings part number for the ball itself.
The "ROM" stands for "Rawlings Official Minor", and the "SAL" stands for "South Atlantic League".
FWIW: I also read that after 1977, American League balls were stamped in Blue ink, while Black ink was used for National League balls.
The ball in question here has blue ink.
Other than just mentioning the ink colors vs. date, I don't know what more to make of it.
Might not mean anything, since pre-1977, they had to stamp the balls with something..
Not sure if I ever got around to posting an update on this one or not.. (Hurricane Dorian and all that.....)
Anyway, I also found images on Google of baseballs with RO, ROM-SAL, RO-A, and RO-N (and now Plug N Play's ROM-TL find).
But back to the original question: Who's signature(s), and is it valuable?
I can't make out either of the signatures.
With some research, I guess one could data-mine all the #15 players in the league over the various years, and see if any of them match up to what those letters on the 2nd signature might be?
I'm assuming it's two signatures. (??)