Do we make this kind of explicit call to l10n.get() in a template function anywhere else in the app?
It seems to me that it would be better to do '<h1 data-l10n-id="preview"></h1>'

That might just work, or you might have to call l10n.translate() on the container element after you set innerHTML.

If we're already doing it this way in other view classes, then I can live with it.