Is there a word or adjective to describe an unnecessary correction? [duplicate]

I think
pedantry
would fit, adjective: to be pedantic

overly concerned with minute details or formalisms, especially in teaching.

I found a possible answer:

Cavil

to raise trivial and frivolous objection

The author caviled about the design of the book's cover.

I would probably go with quibble. You could equally use fault-finding.

Carping is another option, but that's nearly as informal as 'nit-picking', so I doubt you'll like it.

As an adjective or noun, you can use

Picayune

An argument, fact, corner case, or other issue raised (often intentionally) that distracts from a larger issue at hand or fails to make any difference.

I don't like my debating class, the judges are too picayune and Dr. Moss always finds a way to disqualify people based on technicalities.