I don't know if I dreamt it or read it somewhere but is it possible to plan a route in an area (say a canyon or around a lake where you don't live, on the mission hub) and then copy the route and paste it to an area where you live and then test fly the route before you travel to the point you really set the route up for and fly it (after re-loading the proper route of naturaly)? I have not used litchi much but I do like it and I just wondered if this is possible and if so how please?
Unfortunately, I think you were dreaming. Waypoints are created using specific Latitude and Longitude settings. Copying the mission would duplicate those settings.
What you could try is mapping it out and make a detailed note of each waypoint; altitude, speed, curve size, POI, distance between waypoints, etc. Then build that mission again using your test location.
My first few missions using Litchi were very simple. Be sure you really understand what you're doing as the majority of the crashes I've seen were inexperienced users. My first mission ran flawlessly until the final waypoint. at which time the AC decided to make a hair pin turn and started flying away into some trees. Because I had watched multiple videos I knew how to abort. To this day I have no clue what happened!