Instead of reentering your @describe or @history for example, you could go into text edit mode, enter the line number, and either enter a new line to replace the old one or enter "." to delete it.
Instead of using @describe, focus on @nakeds. They're better without a doubt. Then, you're editing only one portion of your description at a time.
For doing anything else, I recommend typing everything up in a word pad of sorts and editing that way. Then you can just copy paste the whole thing and viola. It's vastly easier to edit text in a word pad than on MOO.
A lot of us play on phones. Most smartphones have text editing apps you can download (similar to notepad on a computer). You kind of just have to deal with the tediousness of it. It does get easier once you know the commands better and aren't just learning. I played on a phone for my first two months before I could get my laptop.