Yes that’s right – there are many places in Discourse that will need explicit translation, so I’m logging them as and when. Most recently, we localized notifications for topic titles as well. This is an example of a feature topic I created - Show translated user bios.
I’ll create a new topic and @ you so we make sure we cover all the bases in sidebar.
EDIT: @tvavrda covered here - Translate sidebar documentation links. Please have a look and see if it makes sense.
What do you mean by “switch again”?
Do you mind sharing a video recording (include the address bar) next time it happens? 
Feel free to DM me for this case if the content is not suitable in public. Also, were you logged in? Technically speaking these things are tracked by cookies so it’s a bit puzzling for me.