Disclaimer: I only use the free version of RWGPS
The first thing to be aware of is that the app interface is different to the browser interface (and the browser interface may be different again between mobile and PC versions).
It's not fully clear to me what you want to edit?
Are you expecting to go off your planned route completely and need to be able to plan alternatives on the fly?
Or is it more likely that you'll shorten a planned day, take a slight detour to accommodation and then resume the pre-planned route the next day?
Also are you using a standalone gps unit or RWGPS on your phone for navigation?
Sorry, but I'm going to be "that guy" and not answer your question by going off on a tangent....
Try Osmand. A route planner and navigator. You can mark off (as favourites) your accommodation options in advance. And backups. Then if you need to change plans simply plot a route to your new location.
You can import your gpx files from RWGPS (so you can still do your "big planning" at home in a format you know.
For "on the fly" changes you can create a gpx file in Osmand and send wirelessly to a gps unit (depends on unit) or import into your RWGPS app (I can't test that - please check for yourself).
If you use your phone to navigate Osmand does that too with TBT directions and voice commands.
Osmand works offline (for planning and navigation) a huge advantage in my book. It shows road surfaces and gradients and is incredibly useful. I've used it all through Central & Southern America.
Note: It's not the "best" route planner out there in terms of quality of route but for short diversions it is fantastic - quick, accurate and offline.
To actually answer your question I rarely use the "big apps" on the road. They have a tendency to do a revamp every now and then and functions move around - frustrating when on the road.
The only way to know for sure is to practice. Get out on your bike (or even your car) and recreate the scenario you envisage.
For what it's worth I cycled from NL to Ireland using one gpx file across the UK. At the end of the day I turned off for accommodation and the next morning cycled back to the route. Ditto in Ireland and again going back a different way across the UK. The basic maps on my gps unit were usually enough or I used Osmand.
By the way I've tried out a couple of bluetooth keyboards for touring. This is all typed out on my phone
Good luck