I think picking select2 was a very big historical mistake I would like us to rectify. Instead we should have an ember component for dropdowns that we can easily hack on. It would contain much less code, handle localizations in the same way the rest of our code does and be something we can extend. The CSS around select2 is a nightmare and we often find ourselves !importanting our way out.
Overall picking select2 was a very big mistake. If I had a time machine I would time machine it out.
https://github.com/discourse/discourse/pull/2333
cc @eviltrout