So here's the scenario:
The carlists win the carlist wars, thus adopting their ultra catholic doctrines and grating more autonomy for the provinces, including Cuba and the Phillipines. By the late 19th century they create the viceroyalty of Cuba and the viceroyalty of Philippines, that are de jure independent states but allied to Spain and with members of the spanish royal house as head of state, a governor general appointed by the carlist crown and a native prime minister
If history goes most as it did OTL, with Germany losing WWI and with the japanese incursions in China still happens, how would a spanish pacific affect the pacific war?