So I have a go foil wing that is particularly problematic in terms of getting on the mast.

I have never been able to get it to align with the screw hole. I use it just being held on with the tension of the fit.

I already use a mallet to bash it on and off.

Thoughts on drilling another hole in the wing so that the wing can be screwed in? Or just persist with it being held on by tension?

Good video on GoFoil tutorials on how to reinstall the helicoil insert for the screw. Perhaps after you remove the existing helicoil, fill in hole was th resin/ putty and redrill to align with your wing hole, then fit new helicoil in fuselage following the steps given. I bought a M6 set from Jaycar for $29. Good luck.
www.jaycar.com.au/thread-repair-kit-for-m6-threads/p/HP1606

I had a bit of trouble getting my GL210 onto the fuse at first.

Instead of sanding I put a healthy coat of Vaseline on it..been good ever since.

I sand the inside wing a little to smooth it out and then use the Vaseline.