The biggest problem Kylo has right now is that his leadership just isn’t worth it. It doesn’t grant any real defensive gains, and so Kylo ends up under either phasma (for the crit immunity), Hux (for the real damage increases and counter removal), or DR. This is compounded by the fact that the current stable of Tanks (DS and LS) are simply not sustainable against GAS/Rey without revive mechanics or invuln mechanics (GAS, Rey, and Brute). Since none of these are FO, the Hux nerf makes an actual FO team a nothing.
The simplest fix to make Kylo useful as a leader:
Add extra defensive functionality to advantage based on role. Something like Tanks get % defense, Attackers get prot up, and Support/healers get Crit Immunity when they have advantage. Plays to the FO synergy without forcing full FO.