It really must be said that "Racism Equals Bad" is a near-universal opinion in the West.
Saying "I think the racist chants are bad" or "I don't approve of racism" or whatever, doesn't mean much. It just means "I know what I'm supposed to say because I live in society." I'm sure many of the people yelling "monkey" would characterize themselves as "not racist."
To the wider world, it comes across like Spain doesn't care about racism. Not because they haven't denounced racism. They have. But my parrot can denounce racism too. It's rote repetition with no understanding behind it.
I think you are right in terms of the understanding. Many people will hear others saying don't say this or don't do that but they don't truly understand why it isn't okay to do it or say it and they'll continue to do so in environments they feel safe and comfortable to do so. Spain quite clearly has an issue in that people feel safe and comfortable to be racist and use racist language quite regularly and it's incredibly depressing that people aren't making more of an effort or stand to change that.