Use a different script trigger, e.g. OnRecordLoad to load all values to another set of variables. When you commit, you have both sets of values, before and after.
I would also recommend using existing solutions: NightWing Enterprises - X4X - UltraLog Audit Logging Demo for FileMaker Pro
If the file is hosted you can save yourself a lot of storing all data beforehand and checking later. At the time of the commit, the server has the old values and the client has the new values. With the use of Get(modifiedFields) you can then cleverly ask the server what the old values for those fields were and check the client for the new values, then turn around and write the audit log.
Showed this in my devcon session 2 years ago, so if you were there you already have a working model...
I am not sure about FMEasyAudit, but UltraLog is using Get(modifiedFields), as far as I remember. I am actually working on a simple audit log myself using it, but in this case I ... forgot (damn!). Done with OnRecordLoad way too many times.