They are looking for people to check the route using the route sheet, the gpx, or both - as that's what people will be using on the day.
I route checked 1a North which meant I followed the route and emailed them a few comments about dodgy gpx track points and got a nice reply. No route sheet required.
I guess if I do it I will find flaws in their GPX. I could overlay my actual route with their one and spot any bits where it went awry. That might help them out.
They are looking for people to check the route using the route sheet, the gpx, or both - as that's what people will be using on the day.
I route checked 1a North which meant I followed the route and emailed them a few comments about dodgy gpx track points and got a nice reply. No route sheet required.