Hello. With Odoo 11, we got a language loading problem.
We added a view to res.partner, with some terms who need translation. Initial language is English, and we translated them in french.
After reload the french language, only some terms are displayed in French. The fields labels are in French, but the group titles are still en English. After looking in "Translated terms", I can find the title not displayed en French. So, Odoo know them but didn't use them.
I checked the browser cache and language, the res.parter language, and the Odoo log: Nothing strange, nothing wrong, no error.
Edit: We have the same problem with officials Odoo apps: some terms are translated, in the UI, some not. But all are known in the "translated terms" part.