How could they overcome the language barrier? They could learn the local language(s). It takes time and study, it does not happen overnight, but little by little you can become fluent. Practice makes perfect, or at least close enough to understand and be understood. In most countries there will be commercial enterprises, companies or individuals whom you can pay to tutor you in the local language. Self-study also works. It all depends on you, your aptititude and personal preference, and your pocketbook.
By the way, the official language of Guyana is English although other languages are also spoken there. From the Wikipedia entry for Guyana:
"Guyana is the only South American nation in which English is the official language. The majority of the population, however, speak Guyanese Creole, an English-based creole language, as a first language."
Here's a general Wikipedia article about crime rates in Latin America. It also has many links to more detailed crime statistics, under "See also":
Here's a Washington Post article that if you have an ad blocker, you may not be able to read:
To find crime rates for a particular country, just do a search, for instance for French Guiana:
crime rate french guiana
Then you can do comparisons using the same strategy to see how it compares to where you live, or to almost any US city (like Nashville, TN):
crime rate nashville tn
Many Latin American countries have some pretty high crime rates, especially for robberies, thefts and burglaries. But they also may have lower incidences of violent crime for most people, unless you are involved with drugs and/or gangs and/or illegal activities (presumably most expats will not be).