I haven't checked the specs for 4000 CMOS family recently but I would be suprised if it is cut down to 5 volt levels.
Now and then members try to reuse various old circuitry. Knowing what TTL stand for is handy sometimes..
Look at the old converter between RS232 and whatever You prefer to name it. It's still named RS232 to TTL converter.
CMOS is the fysical technology down inside the curcuit. It's not specifying any voltage level.
What to name the 3.3 volt family? There You might be on a thinkable track.
Caring about users.... You do the opposite....