There's not much Latin America-related material in the letter except for the Panama Canal.
This extremely unpopular but requisite task had been promised since the time of President Lyndon Johnson but delayed because of the obvious negative political consequences. For instance, among the 20 brave men who faced re-election in 1978 after supporting this action, only seven returned to the Senate. This decision strengthened greatly our nation's ties with the people of Latin America and many others within the Non-Aligned Movement who had former ties with the Soviet Union.I "know" that US control over the Panama Canal was a source of division between the US and Panama as well as the rest of Latin America. But, how do I "know" that we got any additional support from Latin America and the Non-Aligned Movement because the US returned the canal to the Panamanians?
Were Torrijos (probably) and Noriega (not so sure) more supportive of US foreign policy in the region because of the canal's return? It's possible that Carter received assistance from other states because of the way that he handled the canal issue but it is hard to imagine that any of that good will extended to Reagan. Campaigning against the canal is one of the most important issues that led to his win against Carter. In addition, Torrijos was dead by mid-1981.
Had Carter, Torrijos or both been able to stick around for a few more years, the return of the canal might have provided longer-term dividends. What do you think?