The AstroPay forms will be translated into several languages. We should have MW i18n available, including parameterized messages, plural, and grammar. The obvious way to do this is to use template helper functions.
We're not using the MediaWiki-core renderer yet, so we're free to play with the lightncandy extensions--at the risk of becoming incompatible with future MW-core. Hopefully, we can work out what's needed, and add it to the MW-core templating engine.
Whatever is done should also be compatible with client-side rendering. I assume this will use the [ https://www.mediawiki.org/wiki/Milkshake | Milkshake ] library somehow.
See the following solution, for the Flow extension:
10:10 < ejegg> Flow uses extensions via lightncandy to do their i18n: https://github.com/wikimedia/mediawiki-extensions-Flow/blob/master/includes/TemplateHelper.php#L141