This is not cloud, hard, sorry that did not help at all.
Let's say you have Beatles Abby Road, personal mix from a CD, so no metadat, you hand typed in song names and album a long time ago to hard drive, and put on your peronsal playlist. You get the remaster, and you burn it from a friend, burn it to a CD, and then replace old version in itunes. Wondering if someone has a methodical system for that.
I get "unknown album", can't find, also itunes seems to have hidden meta, so it reaches for the old version even to the the trash. So you empty trash, but then song names or albums names don't stick, really endless, wonder if someone has discovered a system for this. You might also end up with a ghost version in library, or two version. Itunes will also create new folders for you. You have to rename the new ones several times by hand.... the headaches are limitless. Have not figured out a coherent strategy.