I want to delete several toolbar buttons. Since I write my scripts for several languages, I would like to do this in a language-independent manner, instead of using the pushbutton label. Is it possible?

You can use the number of the function key. Examples:

del P[/8]  // deletes the button that is linked to function key F8

del P[/30] // deletes the button that is linked to function key Ctrl+F6  (24+6)

You can use GuiXT InputRecording to find out the number of the function key, e.g. /30.