are they one of the things that would benefit from using citric acid(or a flavoring with some in it)? specifically, black cherry(tfa)
Black Cherry is better with malic acid but I don't see why citric acid wouldn't do the same. Peach and apple flavors are also good with citric acid or citrusy flavors in small quantities.
this is what i came here wanting to know! are there any known flavorings with malic already in it that are good for this?
I don't know any, off hand other than boosters like sour (tpa/tfa), super sour (wizard labs), malic acid 25% pg (OoO), most manufacturers' sweet tart type, etc.
If you look at the manufacturer's data sheet on "sour" additives or flavors it'll tell you if there's malic acid in it.
As I said, though, I don't know of any, off the top of my head, I'm sorry.
I, personally, find black cherry to be pretty tart, already, so I don't find that it needs more sour, haha. But as we know, taste is subjective and everyone tastes things differently. I have mixed for others who want more tartness...