I want to hide the insertion point and text box boundary in Pages while manipulating the content of a text box with AppleScript

Using AppleScript with Pages, it's possible to create a simple bespoke countdown timer that can be displayed live or recorded for use in iMovie/Final Cut Pro projects. It's just a text box sitting over a formatted shape, with an AppleScript routine writing a new value to the text box every second. Using Pages 10.1 in macOS 10.14.6 (Mojave) it works a treat, displaying the timer exactly as required.

But... when I use the same script on the same document in Pages 13.2 running on macOS 14.3.1 (Sonoma), the insertion point marker and the text box boundary become visible, just as they would if the contents of the text box were being manually edited from the keyboard. In this context, these are unwanted artefacts. Is there a way to make them stay out of sight so that the timer display works like it does on my old Intel Mac, without the boundary line and flashing insertion point cluttering things up?