SharePoint Data Migration

Need help or advice. 

We migrated a client to sharepoint from a users macbook. The migration was a drag and drop style. After about 2 weeks, the client started to notice that files were missing. They could not say which one's for sure but just noticed that some were missing. The total number of files that were migrated, was about 30,000 files and folders. Also the sharepoint folders and files were shared out to onedrive. The onedrive sync on the macbook was erroring out, due to file names and other things.

Since the migration, the client has created new folders and files and edited existing ones. 

I have got ahold of the orginal data from the macbook and created a copy, moved it to a windows machine, ran shareprep on them and used SPMT and put them back on sharepoint under a new folder.

I think I have ironed out all of the file name and length errors. 

But now I am stuck trying to figure out how to get all of the newly edited and created files and folders from the corrupt folder on sharepoint and fix them and get them into the good folder on sharepoint and share it out to onedrive again.

Sharepoint does not show the actual date modified unless it is re uploaded to the folder, from what I can see. 

Is there a way to compare and find newly edited files and folders from the bad data and compare it to the recently migrated good files and folder?