Thanks for the very speedy reply. I wonder why the agent told me there was no valid routing from EZE to Central America on Taca (or any other airline). Maybe I just try another agent.

The United website Star Alliance chart says an intra-S. America flight is 25,000 miles but the link pasted says it costs 30,000 United miles to fly an intra S. America flight on Taca. Which do you think it is?