I have a parawing that just doesn't fly properly. I can't mention any brands and it may have had it's lines changed but don't want to go there. I will probably purchase a later model that just works but still want a better understanding of how they work.
It basically doesn't like flying forward in the wind window especially under load. It is also incredibly twitchy. The tips are always collapsing and it won't turn unless right back in the wind window. I have tried lengthening the middle lines at the bar plus shortening the middle lines at the tips which did help a bit. I have also played with shortening the rear lines at the tips. I have tried other parawings and some of them you can just lock in nice and foward in the wind window and truck upwind.
I guess my questions are:
1. why do kites like sitting back in the wind window?
2. why are kites twitchy in the air?
Thanks
Have you tried lengthening the B cascade (the line-set that is attached to the middle of the bar), AND the C cascade (line-set attached to the rear of the bar)? It sounds like you're describing a slight back-stall.
The best you can do is ask for a line chart from the manufacturer with accurate lengths and then test where on yours it's too short or too long 
