Can a wake vortex off an aircraft actually cause damage to buildings on the flight path below?
Many airports operate mitigation schemes for vortex-related damage, for example Heathrow and Birmingham. Details should be on their respective websites.
If this is at all possible, does the airline involved carry any liability?
As with icefalls, it's very difficult to assign responsibility for a specific ground vortex damage event to a specific flight, so in practice probably not.