Force reconnaissance was not the same as post-battle mopping up

Were reconnaissance cruisers expected to find the enemy and then mop up damaged targets after battle?

Not chiefly; destroyers were expected to deal with damaged targets, while cruiser scouting remained a separate and demanding task.

Japanese cruisers were not primarily intended to conduct force reconnaissance and then clear up damaged targets themselves. Destroyers were expected to perform that latter task after the fleet engagement. A cruiser intended for aggressive force reconnaissance would need fewer aircraft, more firepower, and better distribution of that battery. An aircraft-heavy scout that instead fights like a line cruiser carries its vulnerable aviation fuel and handling areas into the wrong kind of action. Locating the enemy and exploiting a damaged enemy force were separate roles.