Hello Connectibles -
I am sorry to hear about the difficulty with your templates. Our engineers are aware of the issues surrounding eBay's upcoming change of policy regarding active content and we are in the process of updating our users listings to use our new mobile friendly and active content free gallery and counters. Our support team can also assist with that by request if you file a support case from under the Help tab of the site.
As for templates, we are developing a tool to assist with replacing templates but it is currently not available. At present I have no ETA on when the tool will be ready, nor its full functionality, but we do hope to have it available in the near future. Please keep an eye out for more information here in the forum or from an announcement from us for more information regarding this.
Currently, if you wish, you can apply your new template to your Saved Listings and then copy the HTML from from there to replace on eBay in the Revise Your Item form.