Are Spanish people not able to evolve in the way that others are? There is plenty of stuff I've heard and seen in Ireland over the last 30 years that is clearly unacceptable to me now(when it wasn't at the time), but it seems like every time we have these conversations on this forum, there is a large Spanish contingent that just makes excuses for why things aren't racist, instead of just moving with the times. Similar posts from Italians too.
I believe that for this particular case it is necessary to strictly analyze the two radically different phenomena we are referring to.
Your country Ireland belongs to the Anglosphere. It shares language and traditions with United States and Britain, where black face was mostly used to portray a caricature of a black person. The connotations of such an act are therefore very well circumscribed.
The Cabalgatas originated around the same era with no connection with United States and Britain whatsoever. The main purpose was to play the role of King Balthazar, who by the way is the favorite out of the three Wise Men among most kids. Since it was impossible to find people with the same race to play that role, the actors had no option other than painting their faces so the tradition remained.
The main difference is in Britain and United States the custom was to mock black people, whereas in countries with Cabalgatas, Balthazar is admired and loved. Cultural colonialism from United States is huge pretty much everywhere but luckily or unluckily (depending on the stuff they import) they do not influence every country the same way.
To me this a completely different case to Pedro Bravo using expressions like "making the monkey" or "go back to Brazil". And obviously radically different to those disgusting Atletico fans singing "Vinicius, you are a monkey" out of the stadium.