Hello and welcome to the community! 
Yes, I think for your use case the best is to use Defold Mesh component + runtime buffers. You could generate your Catmull-Rom spline with your Lua lib in Defold, then triangulate it to be put on triangles, then push the vertices (and optional UVs/colors) into a buffer and set it on a mesh. Whenever the user drags a control point - rebuild the buffer.
There is a great talk by @mozokevgen about meshes in Defold, recorded and uploaded here, I would recommend to start with it, it’s great to learn about meshes:
Then checkout the other resources:
If you are satisfied with lines or something, there is also this extension, perhaps it could be of any help: