I ran into this issue as well and I am no pro but I did find a solution that worked for me.
I made a child theme. Then I went into my file manager and copied the page template to the child theme but with a different name. Back in WordPress Editor (beta), the new template showed up and I was able to customize it. I used it to create a page template that had no page title.
Someone else more knowledgeable than me probably has a much simpler solution.
Oops, @danquigley thanks. I tried to do as you suggested (via FTP) by inserting the templates with new names and it worked perfectly. Now, I’m waiting like you for an easier and more practical solution by clicking on the “New Model” button. Strong hug