Snap to points and follow line in custom data

[verhovsky]

I'm mapping administrative boundaries using an official (permissively licensed) data source in the Custom Map Data layer and it's mostly just clicking as precisely in the same place where the data source has a node as I can, and a lot of following lines in it. It would save a lot of time if there was a setting to treat custom data like regular OSM data in that the cursor would snap to points in it and let you use the f key to follow lines in it.

[tordans]

This sounds like something where it is worth to spend some time learning JOSM to import the exact data and not re-draw it. Ideally you can find someone to show you this use case by screenshare.