'Settings' menu -> 'Show embedded terminal' item can be transformed into 'Enable embedded terminal' or into 'Always show embedded terminal'. If checked - this setting would toggle appearance of build-in or standalone terminal by pressing 'F9 Term' button. So if this menu item will be checked - by pressing 'F9 Term' button - build-in terminal will appear and if it'll be not checked - standalone terminal will appear.
I don't see any benefit. It just makes it more complicated.
I agree with Alex, it would make things harder to understand. There already are two separate actions to show standalone terminal (F9) and embedded one (Ctrl+Alt+T). Each freely shortcut-configurable. So there is no point to toggle switching between these shortcuts.
Closing this report, after the explanations that were given. Thanks for thinking about how to improve Krusader, Alexander.