Learn Dutch: Niet dat ik je wil kwetsen, maar dit klopt niet. - Not that I want to hurt you, but this is incorrect.

The phrase niet dat introduces a subordinate clause. In Dutch, subordinate clauses require the verbs to be pushed to the very end, which is why wil kwetsen appears at the end of that clause before the comma.

Could I switch the verbs around and say ...dat ik je kwetsen wil?

Yes, you can. When a subordinate clause ends with a modal verb and an infinitive, Dutch allows two word orders. Putting the conjugated verb first (wil kwetsen) is slightly more common in spoken Dutch, but putting the infinitive first (kwetsen wil) is equally correct.

Why doesn't the word order invert after the comma? Shouldn't the verb come right after maar?

No, inversion doesn't happen here because maar is a coordinating conjunction. Coordinating conjunctions (like maar, en, and of) act like a bridge between two independent sentences and do not reset or alter the word order. Therefore, the second clause follows the normal subject-verb order: dit klopt.

I learned that kloppen means "to knock". Why is it translated as "incorrect" here?

While kloppen does mean "to knock" (like on a door) or "to beat" (like a heart), it is also the standard Dutch verb for "to be right" or "to be correct". Saying dat klopt (that is right) or dit klopt niet (this is incorrect) is incredibly common in everyday conversation.