I once had a customer that bred cuttlefish but I haven't spoken to him in a few years. If there's one thing I know he'd recommend, it's to avoid MEI brand salt. He found very elevated lithium and it was killing his embryos. He confirmed it was not from his RO/DI water, but it appeared when he mixed the MEI salt. Once he switched brands the lithium concentration fell and he saw increased survival. MEI refused to speak to him, and would only tell us something to the effect of "there is no problem with the salt. It is the highest quality.". They refused to do any quality testing to substantiate his claims. Their company is terrible IMO.
I know an aquarium curator that used to keep cephalopods though, including flamboyant cuttlefish. I don't think he tried to breed/raise any, but I'd be happy to ask him any specific questions you may have.
There aren't a ton of people who do this, but it's gained a lot of popularity in recent years. One guy I deal with recently tried to hatch some cuttlefish eggs because they were a $15 impulse buy (he was unsuccessful). I recently saw a job posting that was paying $80,000-90,000 a year for a full-time cephalopod breeder. We're going to see a lot more of this coming up.
Woods Hole offers a few species that they breed. They could be a good resource if you are able to strike-up a conversation:
https://www.mbl.edu/research/resour...center/cephalopods/cephalopod-breeding-center