Consider this a reply to both this topic and
This thread made in the general modding forum. Had some thoughts on this.
Assuming a hack for the pathing issue can't be found, I think being able to place aquifer tiles where you want (dfhack aquifer tiles should be able to drain water like natural ones right?) and having your nagas swim to safety instead of drown makes player-based workarounds much more forgiving:
-Purely aquatic creatures can be useful for defense, whether to fill your moat with deadly carp or keep a ranged defender out of melee
-If obtaining resources from aquatic pets is difficult with tricky workarounds they should be part the late game with a correspondingly high reward
-According to the wiki, aquatic creatures won't use nest boxes which is a shame because flooding/draining a hatchery could have been fun
-Air drowning pets can't be butchered and in any case my experience with the succubus mod found it was much more efficient to butcher summoned pets directly rather than wait for them to breed.
-Perhaps ITEMCORPSE could be used? This is starting to sound like a truly bizarre set up but it seems possible to summon a breeding pet which is not useful on it's own but will breed large numbers of another caste that can be air drowned to leave useful endgame items? What kind of bizarre creature of the depths would this be?
-On a practical note, summoned aquatic creatures could be given a temporary nobreath and paralysis syndrome if they air drown quicker than your nagas can pit them into a body of water.
-For amphibious/land pets, consider crustaceans. If dwarves can have boulder crabs, what kind of war crabs and lobsters can the nagas have?
-Giant Sponges. Consider the defensive potential of a wall of tame giant sponges.
-You can have your melee nagas engage the enemy near water hoping to push them into the depths. I wonder if units will path through water once in combat mode in .42 in the same way dwarves will sometimes climb?
-The fact that wagons WILL path through water can be used defensively with a safe water entrance and a trapped land entrance
On some more basic notes based on playing other masterwork races:
-Producing basic furniture and blocks is essential and defines the early game and first impressions. For me, it was getting the ork factory to mass produce bricks, the warlocks making ethereal blocks, and in the reborn succubus mode I refused to move beyond my temporary wooden camp until my slade tower was under construction.
-This suggests that it would be nice if coral production was faster than it realistically should. It just wouldn't feel right to me to NOT have all my basic furniture made out of coral. It's only got a value of 2 which seems acceptable to me for mass production and it's got a stockpile category all to itself.
-A timer based script would still be excellent for coral! Making mass production of coral items very affordable in terms of resources and time would be great but not seeing the results until a season on more would be perfect. You could set a whole load of tables and chairs to be 'grown' with plans to make a legendary dining room but when a larger than expected migration wage comes in expecting beds they're going to have to sleep on the floor for a while. It makes a slight change to the usual early fortress set up.
-Nagas need glass, if only to gaze out into the ocean they should by all rights be swimming in. Or perhaps amber (another underused vanilla material) windows instead?