It does encourage to keep them mobile and running around the battlefield - but once they're caught, they're caught. Maybe it doesn't make that much sense, maybe they just release arrows each tile along their route, but I'd definitely be against letting them just kite enemies, they're too fast to let them ignore ZoC on top of that.

Not sure what is the best solution here gameplay-wise, but still I would like the skill to have some reasonable explanation for the sake of immersion. Swarm can move freely from ZOC --make sense, they are many small creatures, hard to hit them. Infantry has increased damage on ranged -- makes sense, they are trained for melee, while archers are not. Melee charge makes sense as I already described. Archers' bonus vs flying -- ok, clear line of sight, no obstacles, easier to hit, I can find a reasonable explanation. And only the ranged cavalry does not fit in here, since the cavalry charge does not apply here.

What would make sense, I think, is an automatic retreat -- you got hit, you quikly fall back by a tile, but I think it would be very bad gameplay wise, will introduce a lot of chaos and mess up your plans. Unless it would be a prompt with a choice to fall back or not? Or letting the player choose a specific tile? Not sure. Freely leaving ZOC seems to be less of a mess and better gamelplay choice. But maybe there is something else entirely that would have a good explanation and be a good gameplay choice?

A lot of Ranged Cav in Humankind had the ability to move->attack->keep moving, this could work but would either still be a mess to deal with on a receiving side if they maintain their range or nearly pointless if their range gets nerfed.

I'm just really uncertain about ignoring ZoC, because that makes them pretty much immune to Broken Focus penalty outside of rough terrain and people are asking for harsher ZoC rules, so I feel like it could end up making them OP in the long run (pun only semi-intended). Maybe they could ignore only first Retaliation attack in a round instead?

I like both of your ideas, the move back and forth 3+ thing you need to do to get the bonus feels a little off for ranged units