I like Lenni very much, it's quirky and quite a feisty sort of name, though I prefer Leni as a spelling but thats just my personal taste. I’d be inclined to use a longer name like Helena and have Lenni/Leni as a nickname but that’s because I’m old fashioned like that 😆
Lenni Olivia is my slight preference but that’s because I don’t much like the name Sophia (again, my personal taste!). They both roll nicely off the tongue though.
Don’t let the gripers get you down, OP!