Ok looks like I now understand your problem with the database upgrade...
For my a database update is e.g. when a table is removed or added or a new column inserted and so on.
For you a database update seems to also include how the data is stored in the database since you need to read and update the data directly from the database.
Guess I understood it now, but honestly I guess you'll always need to modify the bridge to make it work in the future with new osTicket versions and sorry but as far as I know the developers want to keep the development speed at least with the focus on increasing instead of decreasing, so again, try to work with the API may and get in contact with the developers is still my best suggestion.