Building off of James Coyle's answer, Hint #2 suggests
looking at what the letters in the word COPERNICIUM were originally in the altered periodic table, which are ODJMSFVHHZE. In the case of a repeated letter (C, I), we take the alteration that appears first on the periodic table ahead of the other.
Now, Hint #4 indicates that
we need to manipulate these two strings together to get our true final answer. The manipulation we need to do is clued in Hint #1: we need to take the difference between these two strings. (The other two "differences" are the letters on the periodic table and the different shade of blue on copernicium's square.)
What we have to do then is
convert all the letters into numbers using A1Z26, take away the values in the modified string from the original string modulo 26, and convert back into a letter. For instance, for the second letter we convert D -> 4 and O -> 15, then take the difference between these values mod 26, which is 4 - 15 = -11 = 15 mod 26. This represents the letter O when we convert back.
When we do this for all the letters, we get the actual final answer
LOTHAR MEYER, a German chemist known for his work on the earliest periodic tables.