I have tried unscuccessufly to send page template and tempalte path paramters in page/CMS APIs, both V2 and V3. Certainly there must be an easier way than manually going into hundreds of pages in the web interface and swapping the page template. Does anyone have a suggestion on updated page templates in an API method?
I am looking into this. I would expect that you should be able to use the batch update endpoint on the V3, but I tried myself unsuccessfully. Will report back when I have more info.