Had a look through the factions files... apparently not even the Tritach use Tridents at the moment. So no, they don't spawn.
I suppose part of the reason the Longbow is inactive is because of the fighter AI's habit of spamming missiles immediately. Thunders, for example, will promptly fling their Harpoons on sighting any non-fighter, heedless of such niceties as "point defense", "shields", "flares", or even "occluding rocks". And while Thunders can continue to contribute with their Ion Cannon and Swarmers, Longbows are stuck with just a Burst PD Laser once their Sabot is fired.