I've had items shipped to Germany and Canada (during their mail strike) that took over a month, but eventually arrived.
South America may be a little different. I've shipped to many nations there, and believe that all packages eventually arrived. When I've had people purchase from more rural parts of Central and South America, they often request the package be sent to a friend in the US who will be flying to their location for a direct hand off because the postal service is spotty at best.
Tracking is only available while the package is in the US, so there would not be any further tracking once it arrives in the destination country. It's likely stuck in customs, which can take a while. If it is returned to sender, the tracking will kick in again once it's back in the US.
I've only had two packages returned to sender, both were shipped to the UK. I believe that everything else has arrived safely...