I repaired a cut on my leading edge. I removed the bladder, opened the leading edge seam at the damaged section, taped the tear on both sides, oversewed the edges of the tape, closed the seam, re-installed the bladder.
It was relatively easy to do, but I've been doing my own repairs and modifications for years. I have a decent home sewing machine and the correct thread and tape. I have two mongrel old wings that I have done a heap of work on.
The only hard part is closing the leading edge seam. The seam has a couple of folds and some binding tape. The final step required sewing through about 6 layers of fabric and the repair was on the corner going to the tip so it took very careful sewing to get it right.
It would be a relatively easy job for a professional repairer and probably cheaper than buying the thread and tape and the stress of trying to sew something difficult.
Make sure you choose a repairer that is experienced in lightweight work like kites and wings. Some sail makers are more used to heavy materials and shade cloth and stuff.
If you want to tape it Tear Aid Type A is recommended for canvas and similar woven fabrics. I've used Type B for bladder repairs and that has worked ok.
You could hand sew the tear and/or the tape repair. It's quite effective but you have to be super patient and organised and prepared to lose a little blood.
There's some tips for hand sewing here:
kiteforum.com/viewtopic.php?f=107&t=2412130
All hand sewn through the zip hole, and still going strong after many sessions
