Implemented on staging and live site. I was also able to remove language code hack I introduced while completing T160200, so the codebase just got a little happier in the process. Please verify that this works as desired.

Unless I'm missing something collections don't seem to be working correctly now. The Taylor & Francis collections were blank, but the page has descriptions (https://twlight-staging.wmflabs.org/partners/10/). Even after entering new descriptions for the collections it's still displaying the old text, which I can't find anywhere in the admin interface.

hmm, that's interesting in a bad way. I see what's happening here. It's related to the caching I implemented for the wikicode input. I think I'm keying things in the content model based on language, but perhaps not doing so in the template for collections, since they didn't used to have language options. checking that now.

That little treasure should be resolved. Any lingering outdated collection descriptions will update upon next save.

Did some testing and looks like it's good to go!

pushed to live site.