Were cruiser aircraft successful scouts?

Were the cruisers' shipboard aircraft successful?

Yes. Their Walrus aircraft were capable scouts and helped locate merchant ships for interception.

Cruiser aircraft provided useful reconnaissance over a wide area. The Walrus was a capable scout and frequently equipped these ships. Perth used aerial scouting while operating around Southeast Asia and the Indian Ocean before Cape Matapan. Finding German and Italian merchant ships helped cruisers intercept hostile trade.