Hello Jonáš Hubáček, trunk classification is assigned to main roads with a motorway-like layout in Kenya. The Kitale-Cherangani Road, part of the C51 route, appears to branch out to towns and villages. And when compared to the overall road network, trunk would make the roads stand out relative to similar ones that a) extend across the country or b) connect between major cities and towns. Hopefully that answers your question.

Hello otji73.
Merlin1969 (@merlin1969) was the one who opened the construction here in changeset/154785877. You may want to reach out to them regarding their resources. My changeset (changeset/154845979) was made after merlin1969’s modifications and was intended to update highway alignment to Strava data.
Hope that helps and have a great day!

Hi kibira, thanks for mapping! I noticed here that you classified the following ways as highway=path: way/309435876, way/407979959, way/569778989. These ways are likely accessible to vehicles and therefore should be mapped as highway=residential. Please refer to Highway Tag Africa for more guidelines on road classification: osm.wiki/Highway_Tag_Africa. Thanks, and let me know if you have any questions!