Thank you for your response, DrishT and colleagues. I still welcome your project and your efforts, and hope to be able to provide some hints leading to an improved quality of the data.
I’ll collect some more examples when I’ll work on my data from the holidays.
Meanwhile, you can take a look at
https://www.openstreetmap.org/#map=14/8.5383/99.0690
The 5 “circles” there look like small settlements in a plantation.
I came from North to the settlement in the north-east, via bad tracks, some of them are not yet on the map.
Some roads in that settlement are paved, some are not which can be well detected in the imagery (Digital Globe Premium Imagery).
The “roads” to the west and east should be tracks.
The road leading out of it towards the south was somewhen paved, but most of the asphalt cover has been lost (which cannot be detected in the imagery).
The road in the center of the area leading east towards the major road #4037 is a wide asphalt road (unclassified, or perhaps even tertiary; I did not see kilometer stones or DRR signs there). With the imagery, you can see that (assuming you come from the east) it turns north/right just before you connect it to a track, and at the next junction west/left.
Almost all other “roads” in that area should be tracks.
And it is easy to see that you missed some parts of the circular roads in the settlements.
It will take a few days till I’ll edit that region. My last updates were with the GPS data and waypoints from Dec 7, and I visited the region described here on Dec 23.