CentralNotice includes a ton of fragile and custom code to manage editing banners, and to do translation things. These don't work very well, are not intuitive, are a maintenance risk, and ideally we can consolidate our code with other i18n solutions.
One alternative might be to use [[https://www.mediawiki.org/wiki/Help:Extension:Translate/Page_translation_administration | translatable pages ]], although it's pretty clunky itself.
We need to list our use cases, roughly:
* Banner copy should be collaboratively translatable.
* Banner copy includes parameter substitutions for constant values.
* Banner copy includes localizable strings.