It seems 100% clear to me that Swarm Tactics does not work on huge ships, because huge ships have an engagement value that is separate from their initiative value, so changing the initiative value has no effect on when a huge ship engages.
It also seems 100% clear to me that rebel Han gunner can be used by a huge ship to perform a single bonus turret attack at initiative 7 (but cannot attack again from that turret arc this turn).
Roark, however, is a little in between:
On the one hand, Roark's ability lets you to engage at initiative 7. On the other, the ability specifies "instead of its standard initiative value," which could trip up the interaction because huge ships don't engage at their initiative value to begin with.
I admit that, right now, it seems to be that huge ships will be pretty powerful (especially with their ability to perform multiple bonus attacks before/after engaging) and I don't really want to see Roark enabling multiple initiative kills from a huge ship, so I would prefer that it doesn't work. But I wanted to see what everyone else thought about this interaction, and whether it's possible that Roark's ability will not work on huge ships.