Isn't the fluid amount completely out of whack?

Refineries consume 100 fluid and produce a bit over100 fluid per recipe.
Volatile Resin consumes 1 wood, 1 propagula, 500 water and 100 steam to produce 250 resin.

The water seems arbitrary, water is omnipresent on gleba and pumps are dirt cheap, so that's not a real limiting factor.
Steam? Fair enough.

250 output resin
150 resin for a rocket
500 resin for a grenade
Aren't these amounts crazy inflated compared to base game fluids?

Flamethrower turrets use 3 fluid per second, can a single flamethrower turret really run 80 seconds on a single wood, a sunnycomb propagula and some steam?

I advocate cutting the amounts of resin used and produced by a factor of 5, 10 or 25 to bring it more in line with the base game. (10 would be best if you wanted resin to be ultra-efficient for flamethrower turrets while still allowing fluid storage and barrels to mean something)

The primary purpose of the bulk is to give some logistical "heft" to the fluid, encouraging it to be produced local to its point of use. The flamethrower turret thing is definitely a concern, though, and cutting the resin output scale seems like it's probably the better thing to do than disallow resin use in the turrets entirely.

What's the desired use-case? What type of use are you trying to encourage/discourage exactly?

If you want resin production close to the flamethrower turrets, you're out of luck, I don't think you can achieve that elegantly as long as they consume fluid.

If you want industry closer to your rocket turrets, then you might be better off having spoilable rockets that are as easy to produce as your current rocket recipe. (having an incendiary jelly rocket that slows and burns would be quite fitting for something called volatile resin)

If the goal is to have resin production close to ammo production and science production. I think you can achieve that more easily with a spoilable item instead of a liquid, pumps are just too strong unless you're talking thousands of fluid per craft.

The only primary goal of resin is addressing the lack of native access to coal. Spoilable rockets are an interesting prospect but one I might not pursue.

Then I think you're bang-on right now.