So, what if in 1595 doña Isabel Barreto gets the situation under control and consolidates the Spanish colony in Santa Cruz Islands (OTL part of the Solomon Islands, and they remain a Spanish colony until 1899?
Would the islands population (21,364) be bigger because of Spanish and other European immigration, would the majority be Spanish-Melanesian (some Polynesian) mestizo with Spanish surnames? Would Spaniards have settled Vanikoro and some other of the larger island as well as Santa Cruz/Ndeni?
Would the islands be more developed?
Would Spaniards have created plantation economy to both island groups as British and French did later OTL? Would Spaniards have used African slaves there?
Same questions regarding Quiros's colony in La Austrialia del Espíritu Santo, if it remained Spanish and came to comprise provinces of Penama, Sanma and Torba of Vanuatu? In 1906 it would have gained independence as Quirosia.
Do you think its capital Nueba Hierusalem would have changed its name to Puerto de Vera Cruz in 1906 (after the harbor in which it lies?)
Would SCI and Quirosia ended up as typical Hispanic banana republics with frequent military coups, left and right wing guerrillas etc?