Hello.

I believe in 1.12 there was the option to show combat text on the ToT frame. Also I think you could re position the text with an X-Y coordinate.

Is there a limitation in 1.13 for this?

I don't think it was even working in 1.12 because there are no events generated for these type of units. I also limited positioning to center of portrait or center of the frame if portrait is off.