It's not a choice. In keying the year, you key four digits if four digits appear, two if two appear. It is part of the concept of "keying as seen".

Too many keyers try to infer the century (even when it may appear to be obvious). Our task is to key what is on the image we are looking at.

So, yes, four digits is a problem if it should only be two. Your accuracy will be impacted if the reviewer changes the keying of that field to what appears on the image.

That help?