This might not work at all but I wonder how it would work if you supplied it with a "mixed" language model. That is, a language model based around a person using multiple languages interchangably on the fly, simultaneously, instead of doing this modal switching stuff that causes so many headaches.
Given it's the name, I understand that one of the main objectives of your keyboard is to save space. However an option to simply stack two or three boards for those who could compromise screen space for multiple languages would be nice.
