I don’t understand why react-mdl would force using a string label. Looking at the code, there’s zero reason it can’t be another React component: https://github.com/tleunen/react-mdl/blob/master/src/Textfield.js#L82. It’s just the propType that’s the problem. A bug has already been filed here: https://github.com/tleunen/react-mdl/issues/304.
Could you not also use React Intl’s `defineMessage` to define translations as strings instead of components? https://github.com/yahoo/react-intl/wiki/API#definemessages