I'm not expecting answers to this. I'm just putting it out there as food-for-thought.
While it would be nice to be have full control over tabs in tabbed windows, the thing I want most is the ability to pull a tab out of one into its own window.
I don't use tabs much in Script Debugger or most other apps, because tab management on macOS is very poor and mostly click-centric.
I wrote my own window/tab UI for Safari in AppleScript over 10 years ago, and things haven't improved much.
Keystroke access to 9 tabs helps quite a bit here, but I had done that with AppleScript over 10 years ago too.
Serially moving through tabs is a good feature to have but a pain to use in practice – particularly when toggling between just 2 or 3 of them.
I have a Keyboard Maestro macro that opens the Window menu for any app that has one, and that lets me eyeball the window-list and type-select to pick one. It's not an ideal UI, but it gets the job done expeditiously quite often.
As I mentioned in another thread, I have a Keyboard Maestro macro to toggle between windows 1 and 2 – and I get a tremendous amount of milage out of that.
I will think about changing my tab-movement keybindings to make them more useful for me, because I sometimes used tabbed-windows when working on related scripts.
Script Debugger has wonderful features for terminology discovery and debugging, but it also has niceties – something the app-store has put on the endangered species list.
Please don't take any away, and please consider where you can add some more without breaking your back.
And keep in mind that you're very much appreciated by more than a few of us out here in Mac-land.