Thanks @Al Wilson I am definitely going to talk to a CPA versed in international tax. I will just do a little more research before doing that to get my bearings.
Thanks @Linda Weygant for the example. It seems like the rental SAs my parents have, they have little expenses (which is good because it is more income but also more tax), and also they do not have much savings kept in the SA (probably due to little expenses) which again means more tax.
I am seriously exploring having them change from 'sociedad anonima' to 'sociedad de responsabilidad limitada' which I think is a LLC US-equivalent. If it can be classified as a partnership for US tax purposes, then I think I will be able to deduct the Costa Rican taxes (taken as foreign tax paid) against my individual US income tax. This would help with the double taxation. Also, I read somewhere that it is also favorable when selling because it is taken as capital gains tax instead of ordinary income tax. It would be great if someone can confirm this or comment on this.