Does anypony know of any stories where Maud is in the wrong and/or hurts Pinkie, instead of the other way around like it usually is?

Not that I am aware of, but it is a good idea for a story. We know that Pinkie is well meaning but sometimes overzealous, Maud on the other hand tends to be calm and collected but also a bit blunt at times. Perhaps Pinkie Pie is doing something that Maud might not think is a good idea but Maud dosen't handle telling Pinkie Pie this very well.

6390199
It really bothers me that Maud has never done anything morally wrong in the show. It's made me not like her anymore. Surely there must be fanfics at least?

6390212 She hasn't appeared much in all fairness, I will see if I can track anything down though. People have written fanfics about all sorts of things and some of those have involved characters doing some things that are a tad unexpected.

6390215
Unexpected is better than being forced out of character in both "Rock Solid Friendship" and "The Maud Couple" to make Maud look better. I might be just a wee bit salty

Is it because of "The Maud Couple" that you posted your question? Trust me, I felt that Maud was a little out of line when she continually made promises to Pinkie that she couldn't keep. On the other hand, Pinkie was also out of line when she became emotional about the boyfriend situation and when she refused to listen to Starlight's suggestion for a rational and calm talk.