Translations not being properly saved/published

While testing Babble in [vip-quickstart](https://github.com/Automattic/vip-quickstart) (multisite) I noticed that translations are not being properly published and the frontend switcher is thus using invalid url (with placeholders).

To reproduce:
- Create a post and mark it as ready to translation
- Translate the post and mark it as complete

Reproduce the issue in the linked vip-quickstart multisite setup by creating, translating, and completing a post. Trace the translation publication flow and frontend switcher output; done means the translation is properly published and the switcher generates URLs without placeholders.

Written by the indexing model from the issue text.