I think the raise of the UCR during the early 20th century is inevitable unless the socialists manage to get their act together and become some sort of ATL peronism. And that's a very long shot.
True - I take the rise of the UCR as a give-in. But if we butterfly away Yrigoyen's second term, after Alvear who's left?
Still, since neither party would have the support of the rather aristocratic military, coups are still on the cards - unless the military decisively stays out of politics. The coup against Yrigoyen might actually be decisive there is loyalist officers avert it, maybe even with force.
It's the military staying out of politics that I think is necessary in this case, because the military getting involved with the coup against Yrigoyen that's at the root of where Argentina is at. If the coup is avoided (the POD I'd focus on), that could help out a lot. Of course, there's other problems that have to be dealt with, but getting the military out of the picture would definitely help, à mon avis.
Plus, in any case, that doesn't mean the economy is properly managed. A fair portion of the industrialists of that period were military officers who thought in terms of heavy dual use industry which depended a lot on public expending.
Hmm, very interesting.
Looking back at the 19th century, I think an earlier public education law in, let's say, the 1820s or 30s is not *that* farfetched, but hard to get. The civil wars are unavoidable but, even with it, if a generation or two of urban dwellers get used to kids going to school until, let's say, they are twelve, there might be major changes in the long run. Even if the country isn't totally pacified until the 1860s-80s
That would be interesting to see happening.