On desktop, you can hit a hotkey (Alt/Ctrl + w) to send the nearest word directly to the dictionary to the right, which is a time-saver. However, I think there's also something to be said for some sort of autocomplete, especially if it can take into account the context, previous lines, etc. I'm hoping to do a similar thing with chord recommendations as well.
I completely agree that the rhythm and stress of lyrics would be valuable to analyze. It's going to be one of my major takeaways from today's feedback - I'll just have to figure out a nice clean way to include it!