Hey fellow Africa mapper!
2 things: Please don't convert unclassified through roads to "track", that makes them non-routable for most downstream apps.
If the road doesn't connect with any others then it's fine to convert to track.
Second, don't put a layer -1 on an entire stretch of road unless it's in a tunnel. Even though id urges you to do it, it fixes intersection errors by introducing a new error.
Questions gladly answered - happy mapping! 