Hello, I use Debian stable with KDE and the Colemak keyboard layout, and in Konsole, I have never been able to delete the word in front of the cursor using Alt+D. After filing
a bug with KDE, they helped me figure out that Alt+D is not producing any output, and one other key combination, Alt+R, does not have any output either. Also, in Thunderbird, when I tried to use Alt+D to discard a draft, the combo had no effect, but Alt+S would save the draft. Finally, I was able to test Alt+D on another computer with Debian LXQt and Colemak, and it deleted the word in front of the cursor in QTerminal. I installed QTerminal in KDE, but Alt+D didn't have an effect.
On this computer, when I switch back to Qwerty, Alt+D works as expected, but Alt+S doesn't work. On Qwerty, S is where Colemak's R is. Also, Alt+T doesn't work. T is where Colemak's G is, and Colemak's D is where Qwerty's G is. So it's like all three of these keys don't produce output when combined with Alt whether in Qwerty or Colemak, but it's not dependent on what letter the keys type. I tested a new keyboard, and it was no better. The output of some of my xev is on that KDE bug link.