curvy at small scale?

[_Aka_]

Is there a way to make the angle threshold lower (1cm or so?)

The angle is measured in degrees. Thinking about it as a distance will just confuse you. Think about it as the minimal angle between two rasterized points on the spline. The minimal value of 0.1 degrees is small enough for any reasonable real-time 3D mesh. The issue you encounter comes from something else: the "Min Distance" parameter in the Curvy Generator's inspector
   
As the tooltip says, this is the "Minimum distance between rasterized sample points". Its default value is 0.1m (10 cm), which is too high for your scenario. Lower it and you will have a more detailed (as long as the input spline is also detailed, which is your case already).

I will try, in an upcoming update, to make it simpler to parameter the Curvy Generator to generate very detailed meshes for users who want to work with very small objects like you.