Here are links to a couple of current PB documentation topics that you may find useful:
https://docs.appeon.com/pb2022r3/pbug/upgrading_targets.html
https://docs.appeon.com/pb/upgrading_pb_apps/UpgradingPowerBuilderApplications-Overview.html
The Migration Assistant utility (described in the first link) will check for obsolete syntax without migrating your target(s) to the new version.
The Upgrading PB Apps overview (described in the second link) contains helpful information for upgrading from each release of PB since PB 6.5. You should carefully read through each section beginning at PB 9 and work your way up through all of the sections to the most recent release.
What it boils down to is this: You need to perform the due diligence to try and determine what it will take to upgrade your PB 9 application - nobody knows your application better than you. Any advice you get here is going to be of a general nature. Armeen is correct... the migration should go relatively easy, but realize there are no guarantees that this will indeed be the case in your situation.
Good luck!