Do you have a patch submission policy? The website does not list patches as a contribution option.
I just found Turbo Editor after hunting for a new one - I was using Writer, but it started choking when the word-count went above 5k. Turbo is working nicely for my purposes (writing fiction on the go), but lacks a word count function, so I wrote one that displays a live total and per-session word-count on the editing screen (optional).
I don't think a Github pull request is going to work, as I had to strip out a bunch of code to get it to build in Android Studio on my Linux boxen, but I hacked up a patch that applies on the Version 1.19 release (a1e82b65d42).