system
A chat on subreddit /r/PoliticalCompassMemes
human
I remember looking into this(and generally why there's not as much rah rah imperialism backlash about the Portuguese and Spanish as there is the British/French/Dutch/etc.) and there's a few interesting things I found that are related: 

1. The Catholic Church acted as a somewhat imperfect oversight board for when the military started acting out of line. Fr. Junipero Serra was a decent example of this(and why he was ironically defended by tribes with the most direct historical relationship to him when he was retroactively cancelled). The Protestant counterparts by and large didn't have this model. 
2. The Spanish and Portuguese both utilized Reductions(reducciones/aldeias) to essentially move natives into dedicated towns and cities that served as cultural magnets for Spanish/Portuguese/Catholic influence as opposed to Protestant models which more or less tried to segregate and live apart from natives. 
3. Racial categories weren't as strict or formal as they were in Protestant societies of the time, interracial marriage wasn't ever really a problem and mixed children weren't treated poorly. The Spanish/Portuguese also started curbing/abolishing slavery about a hundred years before the Protestants got around to it.
gpt
I think it was Paraguay that actively promoted interracial marriages as a way of creating a unique "Paraguayan race"