What eight extra treaty cruisers give the Royal Navy

Would fourteen County-class and seven York-class cruisers make a meaningful difference in World War II?

Yes; the extra ships improve global presence, local concentration, and the fleet's ability to absorb losses while sustaining missions.

Eight extra cruisers would matter less as a single dramatic weapon than as persistent coverage across multiple stations. A full County at River Plate and a larger surviving force after losses would give commanders more options without stripping other theaters.