For those wondering, did about an hour of testing with just the dart on this, the most consistent way to hit stick the dart for me was by clicking the mouse down as little as possible when flicking the throw, if I hold it for more than a fraction of a section it bounces, but if you quick flick without holding down the mouse button for too long it almost always sticks

I have found a great solution for this an I forgot to share about it here.

If your dart bounces too much on this level, try changing your mouse sensitivity in game to higher. It made my dart stick to board in like 90% of situations where earlier it was maybe 30%.

Now my mouse movement needs to be slower, but even tho I can't see big difference in dart speed of flight, it sticks much often.

skill