Should definitely use `mozL10n.localize` instead of assigning `.textContent`, however this particular case is a very tricky one, because you'll need to re-localize one of the data keys on language change.

We could get rid of the tricky "doesn't change when language changes" problem by supporting strings being able to look up l10n strings:  I.E. Could the string be `{{_(type)}}, {{item}}` and pass `{ type: fieldValue.type }` instead of `{ label: _(fieldValue.type) }` ?