From memory in its first few years it did have more acts on throughout the evening - but I guess the attendance maybe wasn't all that so it's been settled into the 'one relatively big act at night once the main headliners finish' model for years, which seems to work OK. Been buzzing last few rimes I've been in.
I do think Glasto Latino is a bit half arsed given the popularity of latin music these days both in terms of scope and quality. And the economics probably don't stack up (but they do make it work for african acts). Nonetheless, I'm glad that it exists.
The poster definitely betrays that half-arsed vibe too.