Lets say I create an automation in at some point I see I need a helper I do not have yet, I need to open a private window or on another device go to helpers and create it. Or close the editor and redo all the stuff later maybe. I can not open just a new tab because when you change the tab all other tabs with HA open are also changing.
So why not make it possible to check for helpers you have or create a new one from inside the automation/script editor where you often need them.
For another WTH I created a trigger based template sensor in which you can add variables using an event.
It allows to do just what you describe here.
What browser or OS are you using?
I use Chrome and i can have multiple tabs open in HA and it doesn’t affect the other tabs.
For example i often have vscode open and some other HA page in a second tab. And when i was in the same position that i needed an helper i always just opened a second tab.
But i would also welcome it if there would be a easier way to do this without opening a second tab.