Here is a thread about a script that deals with the range of years:
Perhaps you find something useful.
With respect to the problem of a number of artists becoming various artists: are the artists all stored in the field ARTIST or as a multi-value field ARTIST?
Because: how do you cope with artists like "Earth, Wind & Fire", or (one of my favourites namewise) "Dave Dee, Dozy, Beaky, Mick & Tich" - these are hardly "Various Artists".
Anyway: here is an expression that counts the commas in a field:
"$add($len($regexp(%artist%,'[^,]',)),1)"
So if it adds up to more than 2 you can replace ARTIST with "Various Artists".