Yeah. To turn anything over, you would use retourner. I've noticed that any time you see a verb in French that has the prefix "re-", It usually has a couple meanings: both the cognate form "to return" as well as a meaning having to do with "again", like "to turn again" or "to turn [something] back." Such as a glass.
The same with sembler and ressember. (to seem and to "re-seem!")
"Retourner à" with a location is "to return to...", but it is wrong for "return the glass." I bet the programming on some of these multiple meaning type words must be very difficult. With this verb, you can turn the glass over or upside down. You should not use just "turn". https://dictionary.reverso.net/french-english/retourner
With an extra word it can mean "turn", so "retourner en arriere" is "to turn back."
Not (no longer) if you use the Duolingo app on an iOS device. That has the appalling, deterrent from learning, Health Feature where you lose a 'life' for each mistake. Lose five lives and you are thrown out and unable to complete the 'lesson'. You are then locked out for a period of time. So that, I think, definitely changes it from a lesson to a test.
It also means you are expected to already know everything and not make silly mistakes. Unfortunately, many times, one gets penalised by errors in the courses.
I no longer use the app but use the website version instead. That also has the benefit of direct access to the notes and these discussions.
Yes, that is annoying, I too prefer the web version for that reason, but it was designed to slow people down from just doing a bunch of lessons the wrong way, to make them stop and think about it. You were able to scroll down and choose a tab that would get you to a screen where you could practice previously done lessons to regain the ability to continue.
I'm afraid I found the stated intentions entirely spurious. It now even applies if one is revising subjects after completing the Tree.
The worse case, especially in the French tree, is that there are a significant number of questions where it seems one is expected to already know all French idioms and answers are marked incorrect if a literal translation is supplied. In a few instances, the literal translation should be perfectly acceptable, just not the most common usage. On most other occasions a more literal interpretation is usually required/expected and idiomatic translations marked incorrect. I appreciate that the lessons were most probably created prior to the introduction of the Health Feature, and so not the fault of the course creators, but it makes the app extremely irritating and next to useless as a learning tool - in my opinion.
Literal translations can often be wrong. Here is an article that I find really useful for the many similar verbs like this one: https://www.thoughtco.com/how-to-say-return-in-french-4084862
This source helps me since this dictionary has quite a few examples of the word being used: https://dictionary.reverso.net/french-english/retourner
Then for the more advanced student, there is the French dictionary Larousse:
There are many examples here and sometimes a preposition or another word is required for a different meaning. https://dictionary.reverso.net/french-english/retourner