If you want to see horse highlines in OsmAnd that are tagged with an appropriate tag (e.g. amenity=animal_hitch) but are not shown there, you can ask the maintainers of OsmAnd to add the rendering in OsmAnd. I'm not familiar with OsmAnd because I don't map with my phone; but if you are an OsmAnd user, you can certainly do it yourself. I assume https://github.com/osmandapp/OsmAnd/issues is a good place for that.

If you don't know (and don't want to learn) how to retag your already mapped horse highline nodes from leisure=horse_riding to amenity=animal_hitch or something else, I can do it for you with your permission. But then the nodes will probably no longer be shown in OsmAnd until the rendering of the corresponding tag has been added there. Please let me know what you want to do.