The thing I am going to suggest has nothing to do with the concentrates you’re using in the recipe above.
But it’s rather a suggestion or an idea, that might help you with the recipe.
Every time I am planning on mixing something minty, without just being in your face mint, but still creamy with enough vanilla, I am taking a look at flavors that do just that already.
Not because I’m lazy but most of the times, these concentrates have been balanced by the manufacturer, making it easier to build on, without running the risk of muddling up too much.
As a base I would take something like (FW) creme de menthe, or (FLV) creme de menthe if I wanted a slight chocolate hint in my recipe. (LB) white chocolate peppermint, if I wanted again some chocolate but not dark rather creamier, or a need that hint of cocoa butter to play/push with other nuances.
Another one is (LB) vanilla mint or (PUR) butter mint.
Most of these as stated above give a good amount of both, mint and cream as well as vanilla. Also all of these can be pushed fairly high without too many off notes that even then, can be masked easily.
With that as base, it still gives me enough room to add more vanilla or mint. Even hints of spear mint if that’s what I wanted. Even the suggested marshmallow, but without adding more creams or 3+ different mints at higher percentage, because of the muddle/muting effect.
Now obviously the manufacturer didn’t just put a vanilla mint tic tac under a filter and extracted its flavor, so there are “multiple” flavors/nuances already being used in these concentrates, which will limit your amount of other flavors you can add, but for me that’s a great way to get my mint profiles/recipes the way I want, most of the time.
Maybe something to consider, if not just ignore my suggestion, I won’t be mad lol.