What’s the ferment?? what base??? I think you should share what the ingredients are so we can provide recommendations. For example, if I knew this was a Lactobacillus Ferment, I would recommend a material from BTS such as the BST-Ferment Olive Oil where you would not need an emulsifier or solubilizer.
I find that it emulsify only for a few seconds, I like to increase the emuls.time to for example 5-10 minutes, maybe use a more natural “emulsifier” than polysorbate. Is there any natural and fluid emulsifier/solubilizer?
You can always check the products on the market. For example I googled several two-phase hair sprays and found that they all use combo of some volatile silicone (like Cyclomethicone) + cationic surfactant (like Cetrimonium Chloride).