Better guns do not prevent every carrier loss

Would 4.7-inch dual-purpose guns prevent the Royal Navy's early carrier losses?

No. Courageous and Glorious were lost to submarine and surface threats, while Ark Royal's loss turned on damage-control failures that a better AA battery would not correct.

Courageous was torpedoed while employed in submarine hunting, and Glorious could not be saved from Scharnhorst and Gneisenau by a higher-angle secondary battery. Ark Royal's loss exposed aircraft-carrier damage-control and training problems following the earlier loss of experienced personnel. The Royal Navy learned from that episode, but the lesson is separate from gun calibre. The counterfactual therefore cannot credit the weapon with preventing unrelated failures.