I’ve also found OsmAnd’s bugs/quirks to be extremely annoying; today I tried searching for “dicks sporting goods” when I knew I was within a mile of the store and it gave me one result ten miles away followed by several streets and intersections. I figured the store hadn’t been mapped yet, so after I found it I went to add it and saw that it was already added. It took me a minute to realize that because I hadn’t included the apostrophe in Dick’s the store didn’t show up at all. The only reason the other store showed up is because someone mapped it with the name missing the apostrophe.
It leaves a lot to be desired, and I’d like to develop an app that improves on these shortcomings. I’ll have to check out the alternative you mentioned, maybe a port would be easier than building from the ground up.