I’ve only got my A2 in German so I might also make mistakes with this, but yeah, that seems like proper German to me.
In German, the verb in a sentence fragment always goes in position 2. However, if a fragment contains two verbs (usually when you use the past perfect or when you use a modal verb, in my limited experience) then the second verb goes at the very end. So, technically, OP should have swapped “kannst” and “du”, because kannst is a modal verb and thus needs to go in position 2, but the rest is good.
I also feel like “Zeit für Deutsch lernen” might sound better if it was combined into a massive noun like Deutschlernzeit, but I might be stretching too far with that. The original version is perfectly understandable.
Pretty close, but you skipped some nouns and you have too many "not"s in your sentence. The correct translation is “no, that is the time for learning German. Then you can shitpost in two languages”. Zeit is the word for time, and Sprachen means languages.