What are the certification requirements for software used at airports?
The short answer is yes, With larger airlines, they may own and manage their IT infrastructure at central hubs, so the airline will need to ensure their software works with their chosen peripherals. At smaller airports where this is not possible, many airports use a common use computer platform, managed by both the airport authority and commercial IT vendors. Ultra is one such example. Airline DCS software would need to undergo validation to ensure it will correctly interface with the various devices at the airport: bag tag, boarding pass, document printers, self-check-in kiosks, and gate scanners. 

The Passenger and Airport Data Interchange Standards (PADIS) Board as well as the  
Common Use Working Group (CUWG) provide direction to IATA for creating technical standards. CUPPS (Common Use Passenger Processing Systems), is the IATA standard recommended practice for such common use computer systems. 

DCS systems also must be able to transmit advance passenger information to government agencies, for example TSA to verify the passenger is not on a terrorist watch lists. Requirements for transmitting such information is set by the UN EDIFACT PAXLST specification, but not all passenger information transmissions will be sent from a DCS system. 

EASA and FAA are more focused on flight data (flight plans, ATC, and weather) and have specifications for receipt and transmission of that information, but the transmission is usually done by separate software.