I think 我不明白这里的文化 should be accepted too.
明白 is not usually used for culture, which is something one must experience and may consist of customs the reason for which no one can clearly explain, but for things that have to be learned or studied.
It's accepted now.
Why is 我这里的文化不了解 is wrong?
这里的文化 is the object of 不了解 and has to follow the verb.
Can it be 这里文化 without 的?