What can be used to compare selected cases in celonis with the source system entries

Good morning, could you please provide more details on what exactly are you referring to?

The cases in Celonis come directly from source system entries, if what you are looking for is to validate whether those cases are correct you can simply create a view with the raw tables (the ones that come directly after the extraction) and validate that data with whichever source in which the data is currently being stored (SAP/Gsheets/Oracle etc)