That sounds like a lot of struggle over something the predictive text bar already does ? In my experience when you delete a word, or a whole sentence, it’ll be the only suggestions from the predictive bar at the top of the keyboard. Tap that suggestion and you get your stuff back.
But yeah type another letter and you are fucked…
I think JBL and some other brands do carry such earbuds, but maybe it might not be thz kind of wire you’d fancy. There are also cheaper options that have a wire linking the two ear buds, but as I said those are usually cheap and might not be up to your standards.