In a text related to norms and regulations I read this phrase:
I don't understand this へ particle here. Is really necessary? I think it can be omitted, so what's the difference between への and just の?
It should not be omitted because to say ミルシートの記載誤り would imply that the 記載 is an attribute of or is owned by or done by the ミルシート which is not the case because the 記載 was done to the ミルシート. The literal translation "mention" is misleading because documents can "mention" things but documents cannot perform the action 記載. 記載 refers to something that is done to some document by an actor.
In this case the ミルシート did not mistakenly "mention" anything. Something was mistakenly "entered" into or "documented" on the ミルシート.