Too bad I don't have any to test! I'll get some next order. I know you said it "wasn't quite there," but I'm not sure what's missing for you.
@Clark Kent seems to have some experience with it, and he's adding cake (Nonna's), dough (Joy), lemon (Lemon Sicily) and candy (Torrone) in
his recipe above. Those ingredients might make a pretty decent "lemon cake" on their own, so if it needs that much assistance it makes the INW Lemon Cake seem essentially weak and worthless all-around, to begin with. Maybe that's true, but several reviewers differ, so I'm intrigued enough to find out for myself. Inawera rarely lets me down, but they haven't done much in the cake department before this.
I can only offer generic advice, for now. If it needs more lemon, or more cake, I'd try boosting the end I found lacking. FA Lemon Sicily should work on the lemon end, though I'd probably want to use my INW Lemon or INW-WG Lemon Mix. FA Nonna's Cake or CAP/FW Yellow Cake could boost the cake side, maybe even a little CAP Sugar Cookie. If it's too weak all around, rather than covering it with other ingredients I'd increase the dose, or the steep time, or both. If that didn't work it'd be time to move on. In order to stay in the stash, it has to bring something to the party, right?