That is an example where things will absolutely need to be discussed on a case by case basis.
For the Appalachian Trail, see here, and it might be also useful to have a look at here and here. I suspect that splitting the AT by state would actually match the on-the-ground maintenance situation, but I’m 1000s of miles away and only going on what I have read here, so you really will need to check.
As for licensing, I can only guess that it might do, depending on the copyright regime that the original data was published under, but its complicated.
I’d suggest trying to do one or two initially, involving the local community in each case - perhaps one USA, one European (I’d suggest at least partly in France, because you’ll need to negotiate the issues mentioned here).