Phasma: Easy GW farm.
Resistance Pilot: Easy GW farm.
Kylo Ren: Easy Cantina farm (10 energy)
Fin: Easy Cantina farm (10 energy)
Poe Dameron: Moderate Cantina farm (tokens)
First Order Officer: Moderate Cantina farm (tokens)
Resistance Trooper: Moderate farm (two nodes, Guild store)
Rey: Moderate farm (three nodes, Guild store)
First Order Storm Trooper: Hard farm (two realistic nodes)
First Order TIE Pilot: Hard farm (two nodes)
I've got to say, you're being pretty disingenuous here. There are more easy farms than hard ones, so what you're really saying isn't "Make First Order and Resistance farmable," because they are already. If you ground them out, you could have them all unlocked in less than a month, and half of them at 7* within two months. The only hard part of them as a whole is that you can't really do all of them at the same time (Phasma/Pilot, Poe/FOO, and Kylo/Fin are mutually exclusive of one another).
So what you're really saying is to make FOST/FOTP easier to farm. Which is even more disingenuous, because you only care about them now that they're good characters. If you were really concerned with being able to do mod challenges, you would have started agitating for them to become more easily farmed back in, what, June? Was it June when mods were introduced?