So I've been trying to avoid "fixing" my mixes until they've had more steep time, but this being a fruity one and thinking I already have a good idea of what it tastes like, I went ahead and added a little bit of lemon to the rest of my test batch. Flavors Express is the lemon it turns out I ordered. I tried to go small, 5 drops into the roughly 10 mL that was left. Potent stuff, at first it was tasting like berry lemonade. This morning the lemon has mellowed back so it's really just brightening up the berries as @dc99 said. Just a touch of tartness which I wanted. This is good. Only disappointing thing is that it seems like the Koolada has faded, I still get the coolness but not as much as I wanted. Maybe 1.5% next time.