Username or EmailPassword
It can't be long before they add support for other languages. 8pen were probably either all English-speakers, or aiming for the greatest exposure first. I expect the next releases will just have different layouts for having diacriticals in the default positions, but Greek can't be far off. It would require a lot of research and focus testing, I'd think. I'm curious to see how they do Asian language support, if they ever do it.