In LEI's LE is part of the airfoil. It is not just aerodynamics, but also rigidity in which even slightly thicker structure is considerably better. Ten years ago many LEI's had thin LE wingtips and there was some kites with had very thin LE like Best Nemesis. I had those kites and I liked some of their behavior but there was some undeniably drawbacks as well (twitchiness in gusts, wobblier feel and even collapsing/inverting under heavy loading). Also pumping these kites to over 10psi was quite a task with normal pumps, many light weight kiters (ladies especially) usually couldn't do it. However it is fortunate light weight riders can't load their kites so heavily.
I'm not saying A15 is not a good kite and for the price of it it has to be very good. Of course I could make it better by increasing cell count and perhaps having different airfoil etc., but then it wouldn't be same kite anymore. I meant by redesigning it to fix some not so good things (outdated) in line attachment points and in the bridle, perhaps adding canopy curve to make it more dynamic in flight... It isn't a race kite so why not make it a bit more fun to fly even if it loses perhaps 5-10% of PA?
If later adjustments could be very beneficial they would have been done already by the manufacturer, or even better having taken care the reasons for them earlier in the designing process. It is ridiculous to think that by distorting kite/airfoil to higher camber by tweaking the mixer is comparable to having higher camber airfoil at the first place.
Tweakings are not meant to make a kite, they are for slight adjustments for personal taste or for certain conditions/use. If you have a new very good kite like FS Soul, don't tweak it - for 99.5% probability it would only get worse. Just use it and wait until bridle and lines are settled.
I've flown and tuned couple of Pansh kites. They had slacking Z's which I corrected. Result was slow but quite well behaving kite. I don't think I have nothing to copy from these kites, I've presented here many much more advanced designs than any Pansh kite is