Ok, I just did the calibration and almost everything seems fine, besides the fact that the X coordinate on the onboard mag seems tilted, but it working and that the Y coordinate on the onboard mag doesn't move. the Z coordinate seems fine and behaves like the one on the aux mag.
Well, I will try it again and post the results as I go.
@EDIT: on the second time, things went better, but still wrong.
@EDIT#2: Well, I spent nearly 3 hours trying to calibrate it. I have even used the LP app, alpha version, to try calibrating it and see if something comes up. In the end, the app just seems to introduce many more errors, so I just stuck with my laptop. I concluded that no matter how I calibrate it, and I tried many different forms, the onboard mag may get really good readings and a really low (like 2% or something) error percentage when it is facing one side, but as soon as I rotate it, it WILL begin to give absurdly wrong readings on the onboard mag. The AuxMag seems to suffer from it too, but to a no comparable lower extent.
Is there something I can do?