Two Tervigons is a bit much, but they do poop out a lot of stuff. If you have the Termagant models needed to field that many, so about 75 physical models should do you well, then by all means, have at it. I personally don't like a model that poops out more fodder models. One thing NEEDED if you do this though is E-Shock Grubs on the Tervigons and the Flyrant. That is non-negotiable. You can't touch AV13 except with some claws, and by then the Tervigons will be focused down as the only threat you actually have.
Three Venomthropes in a single unit is a waste. Spread them out as best you can, and since Zoanthropes can't legitimately be cut, two units of one should be fine. Not perfect, but fine. Ideally, for this instance, I would look at the Formations that include Venoms. A Tyrant w/ Toxin Sacs (but can still be a winged Flyrant build), three Venomthrope broods and a Toxicrene, which would fit very nicely into this style of play and is a very cool model. This is all outside your CAD obviously, so you have plenty of slots opened up and since one Tervigon is an HQ, you still won't hurt you CAD in any way. This might be an 1850+ plan though because of the Toxicrene's cost. In the mindset of saving points, I'd just drop one and stick to two units of one each.
I think a Mawloc would serve better than a Carnifex. With as many broods as you're going to be having, the Mawloc's ability to strike inside active combats would be invaluable. If the Carnifex is locked down, that model is basically done for. A Mawloc though is a very talented little bugger and might be the extra oomph you need when the battle isn't swinging your way. The amount of times I've tripped over my own units and been saved by my Mawloc killing the enemy and the last models of the brood causing the hold up is actually pretty high up there. But, I rarely miss scatters so that is also a big factor. I have the crazy confidence in my Mawloc.
I'd cut the Hormagaunt broods down to 15 each. They're not going to live, but they'll hurt something before they croak. Adrenal glands are... expensive. I don't like them for that reason alone. If you have good luck with them, then sure, but I am losing about seven Hormies before I even get to combat and can't afford the dead points. It's not like Termagants and Devs, where only some need to take the upgrade.
If you need more points saved, I'd only run 10 Termagants with Devs. 2:1 is a good ratio statistically for the Termagant broods Fleshborers:Devourers. Weakens them a bit, obviously, but it gives more points for anything else you might need. Devs are only added to my broods when or if I have spare points and literally nothing else to buy. And that's rare. Usually I'll beef up a Biovore squad or something like that.