Yes you'd need to have selected those field(s) for audit - if you had then the changes are tracked in a database table and (relatively) easy to extract, there is even a stock portlet that would allow you to grab the data 'online' but its a bit generic and if you have specific requirements might be better to build your own portlet.
Not sure whether that audit info is immediatley in the Jaspersoft data (I would guess not), but again you could code something to expose it to adhoc reporting.
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BUT if you have not been auditting those fields then there is nothing you can do I think (turn auditting on now perhaps?)