你想多學一點中國歷史 嗎、 你想多學中國歷史嗎 are not ok?
Where does the "learn more" come from? Does the sentence not mean "would you like to learn about Chinese history?"
I think you're right. Maybe the course creators want to emphasize that 了解 is more than just 'learn about' and more like 'have a good understanding of' something.