Hi @axtux and thanks for your query. Great to hear you got some interesting code and up running… would there be any chance to share this code publically such as Github?
With regards to the accuracy, it is unlikely any issues of accuracy are related to the alpha state of the SDK and are most probably down to calibration issues which you can improve via the Calibration Tool included. However, you may have better luck first calibrating in Windows which has extra options to improve the result.
In addition, it is worth considering environmental factors such as strong light sources or windows to one side of the eye tracker. Try to have isotropic lighting if possible. In any event, please try improving the calibration first in Linux and then in the Tobii windows tool if necessary and let us know how you get on. Best wishes.