Gordon Bateson has just made some extremely student-friendly and teacher-friendly
improvements to his Essay(auto-grade) question type and it is now an 'even more powerful, friendly and awesome' plugin.
And
it has been tested to work just as well in English and in Spanish. It
will likely work fine in all other left-to-right languages.
You can download the new code at his GitHub site.
And there is an updated, fully illustrated, Moodle Docs page for this plugin. that shows step-by step how to make an example question with a demo answer and a link to a glossary of common errors.
And Marcus Green has agreed to work on making this plugin work in the Mobile App.