…and Syncthing will listen on 127.0.0.1, and no-one else will be able to connect to it. Therefore she won’t need a password. Therefore everything is fine.
It is ONLY when you want to connect to Syncthing from another machine that you need to mess around with passwords, and ‘emily b. from a.’ won’t be doing this, so this entire discussion is completely irrelevant for her.
That’s not English, and I don’t understand it.
You misunderstand. With SyncTrayor you can set a GUI password, and you’ll never have to type it into anywhere.