The Czech sentence means "We used to go there for nine years.; We went to that school for nine years."
While your translation is technically correct, it would never be said like that in Czech as it implies that you walk around somewhere without taking a single break for 9 years. That's a lot of kilometers without sleeping. (Chodili jsme tam do večera. - "We walked there until the evening." would work.)
If you were to say for example that you walked all the way to Korea and the journey took you 9 years, you'd say "Šli jsme do Koreje devět let."
How would you say "we went there for nine years" in the sense of moved someplace temporarily and stayed nine years?
How would you say a past perfect version of this, like "had been going there" or "had gone there"? I know that at least "We had been going there for nine years" was not marked as correct.
Thank you! I am not always sure enough to claim that an answer should be accepted (I certainly wasn't sure here). Do mods prefer that users submit suggestions even if they are not sure, or is it better not to submit suggestions and float the question here?
The advantage of reporting a rejected answer is that the team can see what your complete answer actually was, and can therefore troubleshoot more effectively. It is fine to report and also to comment, if you have a specific question.