Hi Ihab,
You can go to the Motion Tracker> Graph View and get a very precise idea about the quality.
Manual
https://help.maxon.net/us/#54623
Tutorial
https://www.cineversity.com/vidplaytut/motion_tracking_object_tracking_inside_cinema_4d_motion_tracker_graph_view
The number you mentioned is certainly a helpful indicator, if you have the same quality of footage for each shot. It is however, a value that measures the calculated model of the scene with the derivations of the accepted (i.e., not deleted) trackers features. Since foreground tracking features are more precise than background features, the comparison stops if the shots differ in this regard. Furthermore, we see more and more 8K productions and less HD source files these days, while the quality of 4K or just UHD footage has a wide variety of its own, i.e., heavily compressed (perhaps even stabilized, etc) or raw footage. Another difference is given with lenses (wide or long for example).
If then downsampled or in some cases even up-sampled footage needs to be compared, it is not simple to just put a factor to it, to be comparable. Hence, why I suggested to go with the 2D tracking error values, which seems to be the best place to evaluate and optimize the result for the 3D Solve. Missing the single error number seems to validate this idea. Besides, we see a change of that value over time, like in the little graph that Syntheyes has had introduces a while ago in the lower right corner.
Anyway: The right place to suggest this feature would be here, and if the developer see an advantage in it, it might be put on the to-do list. … and yes, while in other apps, this value gives me always a good feeling when it is low. But beware of talking it too seriously, to just get it down, might jeopardize the quality fo the camera path.
So, please voice your wish and perhaps others do so as well.
https://www.maxon.net/en-us/support/suggestions/
My best wishes
