I worked as a RoR and JS developer on several codebases that involved I18n, and my conclusion so far is that it is better to avoid such multi-lingual projects because there is nothing interesting to learn/meet from engineering point of view (unless there are other aspects unrelated to I18n). For a developer, I18n in codebase just means manual boring work that cannot be avoided or automatized. Occasionally, there are funny glitches, when people unfamiliar with the domain copy&paste translations via google translate, but that is all.
But maybe I am wrong and there are some interesting engineering problems other people have met and addressed while dealing with I18n?