I'm sorry to hear that. 
Thanks for giving it a try. (I've been wondering if it would work.)
I was also wondering if anyone else would like to see the ability to trigger a conflict palette bumped up on the developer's to do list.
From this post:
"I understand the desire to trigger the conflict palette from a macro (its actually on the todo list), but currently there is no way to do it directly.
Probably if you use an AppleScript to simulate the keystroke, that would reliably work to trigger the macro (since Keyboard Maestro would then not be trying to get the latter behaviour)."
Back then, the AppleScript failed too when forum members tried it, with garnering this:
But I found that two AppleScript calls got the message through to KM and was hoping it would work elsewhere.
It seems that having such a thing might allow for making something like the posted video describes.
An initial conflict palette would serve as the "safe input area".
A chosen item could store another id to yet another palette. The "leader key" macro after having launched the palette would be paused to listen for any keystroke with "Pause Until the Key State Changes". The pause would end when an initial character item on the palette was typed. The "leader key" macro would process the stored id and so on.
I hope that makes some sort of sense. All of that actually does work on my system.
I'm sorry to hear it doesn't fly on Sonoma.