Sounds good, Frederik.
There is one factor which affects the tacking symmetry a lot:
The sheet-point's sideways offset. Apart from this, one must ensure that the batten parrels are not slack, as slack parrels make the sail appear to be sheeted more in on the mast-to-weather tack.
Increasing the camber.
On my Ingeborg I also measured the initial camber/chord to 7%. Since I had tied the sail fairly taut along the battens, I decided to ease that tension with about 4cm. After that, the camber was found to be 8%, which was what I initially aimed for.
I don't know how you have tied the sail to the battens, and I don't know what camber the Tuchwerkstatt cut the sail, but in case you have tied it taut along the battens, you may as well correct it and get a bit more drive. The price to pay is a bit more wrinkles along the battens.
Arne