Parts of southern and central-western Brazil also drink Tereré ("Tererê") with fruit juice, most tipically lemonade, so I'd guess there may be some other places here and there in South America where that's also regionally true

In those same regions a sort of sweetened hot mate drink is typically made for children. Do you have that in Paraguay? It's called "Mate-doce", and I'm pretty sure it's not related to what you described as "cocido", which I've never heard of and sounds like it prepares the leaves in a different way

Does anyone have a 'recipe' for this cocido? I'm curious to check it out