I think they were meaning more along the lines of, if a casting attack is going to deal physical or magical damage then it will look different. Which would be a more major UI change and if the damage isn't fixed to one type until days before the patch goes live, then I can see that being an issue.
They mention a 'pop up window' even, so what was being asked was quite a change to the current system.

What you mean is changing the colour of the floating text after the damage has been applied, to signify that it's magical/physical. It's after the fact, but allows you to learn without additional steps.
This is probably easier to implement, but it doesn't seem like that's what they understood as the question.