The only problem you'll encounter with using it is if you have some code that relies on the __AVR_ATmega32A__ macro since the __AVR_ATmega32__ macro will be defined instead.
Actually, I've no idea where the __AVR_megaXX__ is located.
*cpp: -D__AVR_ATmega32A__ -D__AVR_DEVICE_NAME__=atmega32a
I've curious to find out if there even exist such a definition as __AVR_ATmega32A__.
When I developed this core I used this device signature list to make sure all variants was included.