That is a limitation with Routines. Most people don’t care, would guess 85-90% of people have a single thermostat.
I have 2 Nests, and when working on Nest manager we added a rule engine to handle this situation.
I believe you can use CoRe to do this. If Mode home then set temps accordingly. If you get into deep home automation you will eventually need to use CoRe. (http://thingsthataresmart.wiki/index.php?title=CoRE)
There is also this which may work if you want to avoid Core.