I am American but I have traveled to Guatemala several times. I watched the episode several times, trying to figure out if it was filmed in Guatemala itself. Only after reading other fan reviews was I convinced the actors weren't filmed there.
One commentator mentioned the unlikely scenario of a young boy knowing about baseball or the Cardinals.
Since we adopted our son from Guatemala when he was 11 years old and brought him home to St. Louis (the Cardinals' home town), I completely agree this awareness was unlikely. Our son was raised in Guatemala City, where the Internet was very available, and yet he didn't understand what or where the US was and he didn't know about baseball. He became a baseball fan after his adoption..soccer is the big sport in Guatemala.
I agree there weren't many indigenous faces in the extra casting. I did see efforts at Mayan clothing and I was glad they didn't have all of the extras wear Mayan clothes because most of the younger generations don't wear traditional clothing unless there is a special event. Regular native dress is more likely to be see in the older generations.
I am unable to respond to observations about the Spanish accent being "off" for Guatemala, but I know there is a big difference in the accent (and many words) from Mexican Spanish.
In the last decade, I have seen a number of shows try to represent Mexico, but it is rare for network shows to try to show Guatemala. My review is based, in large part, on the clear evidence that this show tried to represent the country.
Some have commented that they thought the show was lazy in not filing in Guatemala but it is important to remember that the episode was filmed during a pandemic. Their home base is in Vancouver and Canada has/had a number of restrictions regarding leaving the country and returning to Canada.
I am fairly certain it would have been a logistical nightmare to film these episodes in Guatemala during the pandemic.