Other than the official courseware there are no prep resources for the CCTE Exam which is a fairly new specialist exam. You can purchase the CCTE courseware yourself for $400 USD at https://catalog.checkpoint.com, select Training...Courseware Kits.
Keep in mind that the CCTE course revisits the CCSE course topics from a troubleshooting perspective, so make sure you are up to speed on the CCSE topics as that will help. Also some of the CCTE content was pulled in from the deprecated CCSM class, for which there may still be some resources floating around. Good luck.
Updated 2023 IPS/AV/ABOT R81.20 Course now
available at maxpowerfirewalls.com