Translation:The day before yesterday, we learned what had happened in our bedroom.
Is 'the day before yesterday we got to know what happened in our bedroom' a suitable translation?
I think the plusquamperfect tense should really be used as in the official translation.
I understand your point, and thanks for your answer, but my question mainly referred to the verb: Is 'to get to know' a suitable translation for 'dozvědět se' such as 'to find out' and 'to learn'?
"Get to know somebody/something" is a phrase meaning "get acquainted/familiar with somebody/something". It is not really used in the sense of discover something.
I wrote 'We learned the day before yesterday what happened in our bedroom'?
They may want to enforce the proper sequence of tenses here. The Czech puts the action in the subordinate clause in the past with respect to the main clause. In English the past perfect is used for that, although colloquially it's very common to use a relaxed sequence of tenses when one need not be precise in order to be understood.