Could conventional carriers work in the North Atlantic and Baltic?

Were conventional carriers unsuitable for the North Atlantic and Baltic?

No. They worked in the North Atlantic, and in the Baltic the stronger question was whether land-based air power made a carrier unnecessary.

A commenter argues that catapult-assisted and flying-off-deck carriers were unlikely to function in North Atlantic and Baltic conditions. The reply points out that the Royal Navy and US Navy operated conventional carriers successfully in the North Atlantic, and that American and French catapult carriers continued the concept. For the Baltic, the mission matters more than the machinery: land-based aircraft could often provide the same air cover without exposing a carrier. The Baltic also offered room for a ship of Graf Zeppelin's size to maneuver instead of forcing every launch into a narrow channel. The equipment question therefore depends on force employment and geography.