@marisa59229 Thanks for posting this question! 
I had the very same concern. If we set the text scale to be 40 - 60 px on ‘Desktop’ and then switch to ‘Tablet’ or ‘Mobile’ breakpoints, the text scale still only displays the range i.e 40 - 60 px instead of the ‘actual font size’ that is displayed on the tablet screen.
As you rightly pointed out, it can look odd on different breakpoints and any indication on how we can set ‘different font sizes for different breakpoints’ while still being able utilize the ‘scale text’ feature would be immensely helpful.
One workaround that isn’t perfect is to go to the ‘Desktop’ (largest breakpoint)view and make a note of the correct font size for this display. Then do the same for ‘Mobile’ (smallest breakpoint) and then set the text scale feature ON with these values. But again, we still run into the problem of the in-between breakpoints since we are unable to see or adjust the font sizes for these middle breakpoints since text scale only favors the largest and smallest breakpoint. The middle person always loses out in this case 
Thanks again and any help would be Awesome!