Is there a way to import camera tracking data, like .json or .jsx files into Blender?
You can certainly do this the other way round and export to After Effects (*.jsx) using the Adobe After Effects plugin but it hasn't been updated for 2.80.
This has been investigated before please see Does Blender 2.8 have a working import-export plugin for After Effects?
The only truly supported format for tracking data import is *.bvh, again via add-on.
You can always modify the jsx script to import instead, but as it stands I donn't know of any native way to do what you ask.
Perhaps look at this addon from the blendermarket