Shisha Vanilla… it’s sooo good. But Vanilla Bean Gelato would be good in that recipe. Vanilla Bean Ice Cream would be good too. But, in my opinion you might be getting away from the lightness of the recipe if that is what you are after. My suggestion to you would be to make a 10ml bottle of each of those vanilla flavorings and make the recipe without the vanilla. then in a separate bottle, mix the Berries portion of the recipe with the Vanilla single flavor mixes one at a time and see what you like. You would gain a little understanding of how each of those flavors dance around with your flavor profile.
Another suggestion… Bite the bullet and order Shisha Vanilla. It is a flavor I think is a must-have for anyone who likes vanilla.
As far as the strawberries go, I mix as @SthrnMixer and @JoJo has said with Ripe and Sweet sometimes. But I also use Ripe with TFA regular strawberry too. It just depends on what I am mixing. Sometimes it is just me screwing up when entering the flavors into the calculator too