Extracting full name (with changes)

I've been able to successfully extract the surname of a user account using this formula: UserToName([Record Owner], "FF")

The problem is that the user account was created as first name Richard and the contact record that corresponds to that user was set up as "Rick", so I'm not going to be able to make a match.

My goal was to compare the record owner to a snapped value that occurs in a previous process, but when I tried changing the actual user account to Rick to circumvent the fact that the snapped field it is comparing to will not change, but apparently once the user name is set up it doesn't change.

Is it possible that the user account will update after some period of time? if not, I'm open to other suggestions/ideas, and I thank you in advance for your input.