A theory like this has been making the rounds since at least the 70’s when I first heard it.
The problem with this theory is that geneticists should have found african dna that dates back a thousand years or more among central american tribes. This may have happened but I have not heard of it.
Another variation of this relates not to olmecs but rather to the mayans whose temples look strikingly like temples from Indonesia. But once again I have not heard about any confirming DNA evidence that would link the two peoples.
Does anyone know how much genetic testing has actually been done in Central America. I have heard of European studies where a lot has been explained based on 1600 tests. Also, I am not suggesting that a lot of Africans made it to Mexico. All it would take would be one or a few very powerful warriors who may have survived a more general disaster or fighting to pull this off. Sterility, castration, or injury might result in lack of offspring. A few black females on board for the black mercenaries could keep a pure blood line that died out or was killed. Lots of ways that it could have happened.
Also, I agree about the Asian traces. I saw an exhibit at Epcot Center in Orlando, FL. There was a ceramic cup with what looked exactly like a Japanese figure. [I took one year of History and Appreciation of Art, which included Asian forms.] I have never had the impression that Mayan temples looked like Indonesian ones. Although I have not been to Yucatan, I have seen many illustrations/photos. Which temples did you have in mind, both the Mayan and Indonesian? I have seen the pyramids/buildings at Teotihuacan, Monte Alban and Mitla, walked in them and on them.
Schoch make the comparison in his book:
There are more pyramids in Mexico than all of the rest of the world combined.