I’ve been to Colombia, the shampoo girl at my hairdresser is from Guatemala, the cleaning lady is from Bolivia and Dora is from Peru. I have no problem understanding or being understood by any of them but I’m sure there are modismos peculiar to each. Had no problem in PR either. Haven’t been to Mexico prob 25 yrs though.
We were in Puerto Rico when my dad was in the military-other than a few differences in words for some food items and the fact that they talked a bit faster than us Nortenos, none of us had any problems with conversation-the people I’ve known from Cuba spoke Spanish even faster, though...
I haven’t been to Mexico in about 15 years-since it became too unsafe to get into my Suburban on vaca time and wander around going to archaeological sites and visiting friends and relatives-but in the interior there were still dialects spoken only in certain areas-difference in accent, slang words, idiomatic expressions, more formal speech etc-I’ve always found the way a language develops differently over an area fascinating.