I've had Nicaraguan food a couple of times, once at an unremarkable place on Fairfax, I think, near the 10, I cannot remember the name, but the meat was all cooked well past death. We had some kind of mixed platter and I didn't really enjoy anything on it (maybe that wasn't the thing to order there?). Many years ago I went to a place (maybe on Pico) called La 27th. Again, over cooked but tasty meat on the Fritanga Platter (maybe that's just how they do it, or maybe a platter of various meat and sausages is just not the thing to keep ordering). I do remember -- and still think fondly about, one thing we ordered there. I remember reading it reviewed as "the most delicious vegetable preparation ever" or something very near that -- and it was. It was a hollowed out zucchini, stuffed with fresh (squeeky) cheese curds, battered and deed fried. Delish.
I'm not sure exactly how similar most central american dishes are, or how much cross over there is, but I have had excellent Honduran Food at Lempira Hondureno on Hollywood Blvd (there are a few write ups you can search for), and I also really enjoy the El Salvadoran dishes from Atlacatl on Beverly. Not sure if either of these will scratch your itch, but if you can't find good Nicaraguan, maybe these will get you close.
301 N Berendo St, Los Angeles, CA 90004
4848 Hollywood Blvd, Los Angeles, CA 90027
The place on Fairfax near the 10 was on La Brea (El Nido). Still there, but switched to Salvadoran about a year ago I believe. Anyway, La27th (no idea what that name means) is the place for this fare in town. I don't want to start a battle here, but my experience from eating a lot of meals around Nicaragua is that most of its cuisine is shared by its neighbors, so hitting some of the Central American places west of downtown should get you what you're seeking (aside from cacao I guess).