If you utilise the WCM Core Components V2 Page, as your websites base page during the creation of the editable templates, you can utilise the editable template's Page Policies to set specific client libraries for different templates; it's that simple. You can define specific client libraries directly from the Touch UI editable template page editor.
Here are steps for how you can include a custom client library for your editable template (let's use we.retail example project):
From the Touch UI editor, click on the drop-down button from the left top main nav, and select on Page Policy; you are presented with the Page Policies configuration page. screenshot illustrated below:
Next, add your client library category directly into the client-side libraries multi-field, and save. screenshot illustrated below:
Going live: Publish the editable template with your changes.
Going live: Flush the cache, if your website is sitting behind a dispatcher.
Going live: Flush the CDN cache, if your website is sitting behind a CDN.