Reading up on the evaporative emissions system, it's hard to see how it could cause any running issues.
Effectively, the fuel tank "breather" is connected to a charcoal filled canister, mounted at the rear of the engine. This canister has a vacuum operated diaphragm that can open and control gas flow through the charcoal canister.
The purpose of this canister is to absorb fuel vapor that naturally evaporates off the fuel. To enable this fuel to be removed, there is a solenoid valve mounted on top of the throttle body, and when this is energised, it allows engine vacuum to open the canister diaphragm valve to allowed the stored fuel in the the charcoal to be pulled out and burnt in the engine.
Apparently, this only happens when the engine is above 70C, and it's unclear whether the solenoid valve then stays open all the time when above 70C.
The P0443 fault indicates a problem with the solenoid valve, but it's unclear how the ECU would know, unless it has a method of monitoring current flow on that output.
Apparently there is a pressure / vacuum relief valve built into the filler cap in case the evap system fails, but that puzzles me as well. I'd always assumed that the "pffffft" noise when undoing the filler cap was positive pressure inside the tank escaping, but the action of the evap system would suggest that it is, in fact, a negative pressure (vacuum) in the tank - which you wouldn't think would be good for a pump to pull from.
So, what could happen to the evap system to stop it operating? Well obviously the solenoid valve could fail to open, but that wouldn't be a problem to the engine as it runs quite happily without it when below 70C, so I would doubt if the engine would notice if it had failed.
Do check the rubber vacuum lines on it though, as a split would allow unmetered air into the engine and that can cause a few issues.