I have the same foil, and did similar damage to it when it was just new (dropped it on the road and smashed the tip).
I repaired it and over 500 hours later it's still going strong. I love it and wouldn't ride anything else.
Seems to me the repair process is pretty much the same no matter how you go about fixing it.
Clean up the end and remove all the broken bits of carbon.
Use a pin to scrape into the cracks and chips. Make sure any little particles are removed. Probe the cracks and see if they go through to the foam inside. Don't be too vigorous. You don't want to damage it more. Just clean it up and explore the damage. A magnifying glass or jeweller's loupe is very useful. Use lots of light.
If you find any pinholes that go to the inside (the pin goes all the way in) then it's good to get a syringe and inject epoxy inside to seal it and reglue it.
I use West epoxy with the slow cure catalyst.
If it's all sound then fill it with epoxy paste. I use this stuff
www.bunnings.com.au/pc-11-56g-white-epoxy-paste_p1560098Read the instructions.
www.pcepoxy.com/products/permanent-repair/pc-11-paste-epoxy/ You can smooth it out with metho or just a wet finger. It sands really well. It's a good idea to mask off the damaged area to reduce sanding and to avoid too much sanding of the unrepaired section.
If there's any big gaps you might want to get a sheet of carbon. Cut up a bit into fibres and use it as a thickener and gap filler.
If it's really badly damaged then you'll want to laminate the tip with the carbon. Finish it with a top coat. Maybe some filler to smooth it out.
If that comes up well then just paint it with Dulux Duramax white paint (or not if you don't want to). The mongrel camo look is pretty cool.
You can find videos for all this on youtube. You can buy all the bits and pieces from Bunnings and/or surfboard shapers supply web sites. There a couple of those in Oz.
Plan B is send it back to J Shapes in New Zealand. It's not too expensive to post a foil and it'll cost about $100 plus postage.
Questions. What are you going to do with the graphite? It's a lubricant. I guess you could use it to colour resin.
Why do people think 30 knots is strong wind for foiling. A 4-5m kite and that foil are joy in conditions above 30 knots. It's made for fun in the waves.