Hi, I keepthe occasion of this thread because I have exactly the same problem:
with Adonit Pixel, Ipad Air 2, screen size 9,7".
The wavy effect of the line is proportional with the velocity with wihich I draw the stroke:
slower is the stroke, more wavy is the line; If I draw it fast, the line resilt more stright.
Moreover I can't findany way to set shortcuts on the two button of the pen and I'm wondering if there isn't a more comfirtabke way to connect tne pen than to enter in the Preference menu, scroll down and select Connect....
Thanks for the attenion. The app looks great and I really hope to be able to use it correctly.