what is com.apple.coresymbolicationd in caches?
Symbolication means replacing memory addresses with symbols (like functions or variables) or for example adding function names and line number information. It is used for debugging and analyzing crash reports.

/System/Library/Caches/com.apple.coresymbolicationd/data was also about 600 MB on my account, so I guess it's normal. Deleting files in cache folders is generally safe, and /System/Library/Caches/ is even excluded from Time Machine backups.