It was actually suggesed for the default task switcher https://bugs.kde.org/show_bug.cgi?id=76356 Basically instead of cycling between the group tasks and minimize, you cycle between the group tasks and the most recently opened window. So if you have terminal open in the foreground and two browser windows open in the background, clicking three times on the browser group will get you back to the terminal window.
this is supported in Latte git version