When it comes to Spain, from looking at your setup, I'd highly advise you to make sure Morocco plays a major role in defining Spanish affairs in this timeline. Spanish Morocco alone was a resource drain and causer of controversy in the OTL due the constant wars and rebellions in the region, along with the government effectively losing control of the entire protectorate until the French intervention in the Rif War. With Spain holding the entirety of Morocco here, things are likely going to be even worse than they were in the OTL dealing with the revolts the French also contended with, especially if an event or events reminiscent of the OTL Rif War take place. Will be interesting to see how Leopold/Carlos' Spain plays out too, considering that despite remaining neutral throughout the great war Spain was in a constant period of crisis. You've got the opportunity to create a totally different Spain here. 1 long served monarch rather than a republic, 3 monarchs, and a regent. Not to mention the constitutionalist Bourbons now thrown into the opposition rubbish heap with the Carlists. Best of luck with your work.