Bugtracker is probably one of the most complex packages to attempt to modify in OpenACS.
It looks like you got pretty close, but you probably just need to debug a little more closely exactly how the data gets inserted into the database.
Just adding the new parameter won't affect unless you find the query that actually does the insert and also change that.
Also note for objects you don't want ot just add a column to the table, you need to create the object type attribute, in this case I believe bugtracker uses the content repository.
