Button click handler assembles a list of ticket ids, submits them via ajax, creates a flash msg, then...reloads the whole page?! Why not do a regular form post, controller-side flash msg, then redirect back to the referrer. May still require some client-side shenanigans since we're posting values from two different forms.
Fix checkbox inputs. Instead of using the ticket id for the input name, use ticket_ids-n, then use formencode to variabledecode and convert to a list.
There are at least two edit and update_tickets methods in tracker_main.py that look similar. Can they be DRY'd up?
When making a mass edit that updates a user-type custom field, the comment on the ticket is : ****: user02 --> user03 (**** instead of the field name)