I get email from people all the time, saying "how can I help fix my local area of the global scenery". With OSM, you can help., by improving OSM's source data.
Here are two things that will matter in the quality of generated scenery:
- The oneway tag. Roads that are one-way need to have this tag, or the conversion to X-Plane might have an incorrect two-way road in place. If you don't see the one-way arrows on the OSM map rendering then this tag might be missing.
- The layer tag. When roads cross, "layer" tells OSM which one is on top (and that they do not intersect). Similarly, if a highway is underground, it's because it has a negative layer. If the layer tag is missing, complex intersections will probably render as junk.