Hi @ziriax, thanks for your message and glad to hear about your project.. do you have a GitHub page for it? Certainly, this would allow us to try and reproduce the issue you described. Also, how are you performing calibration? Is it the same process for both experience app and the stream engine application?
Also, how are you judging the precision within the Experience App? The gaze overlay ? This has built in smoothing filters whereas the stream engine (Depending on the gaze stream) reports either raw or lightly filtered data.