Try to get a Solve Error of 0.6 or lower
They don't provide any camera information and especially the Focal Length is missing, so you'll need trying out what works.
1. Find as much points as possible in the face to track
2. Tracking Settings
Have a look in the Tracking Settings to figure out what works best.
In this case the Fast Motion preset works really fine:
You can also change the Tracking Speed in the Extra Settings to switch from Fastest to Realtime:
This helps during the tracking process to see when a tracker looses the point.
3. Refine and Cleap up
I figuered out that refining leads to an incorrect lens distortion in this case. Also there is no need to refine K1 and K2.
Find Tracks with a high Average Error and remove bad tracks for a solid solution:
At the end this should lead in a robust solution.
I was able to get a Solve Error of 0.57 and all the tracker are well positioned in 3D space:
Good read: How can I get better results when doing camera motion tracking?