Thank you for the feedback, and I'm sorry to hear about the inconvenience this new Template system has caused you Because many customized listing templates contained active content, they were not transferred over into the new template selector automatically–but you can make them available in the new system.
1. Go to the template "Management" page.
2. Click the "Edit" button of the custom template you want to be supported in the new template system.
3. Copy the entire HTML of that template.
4. Hover over the Listings tab and click "Create New" in the "Custom Templates" section.
5. Past the HTML of your customized template and click "Save As New".
6. Now when selecting a template to use, you'll be able to access that custom template in the "Custom" section of the new template selector window.
Again I'm sorry for the inconvenience, but please let me know if you have any other questions/concerns.