A search of PubMed identifies very few examples of adverse health outcomes from folic acid consumption.

The main one is folic acid masking Vitamin B12 deficiency. Even this is very rarely seen and is more of a theoretical adverse health effect. There is not an increase in impacts of Vitamin B12 deficiency in Canada or the US, despite folic acid supplementation. The second was two examples of patients where folic acid supplementation interacted with anti-folate chemotherapy drugs.

There are simply not a plethora of overseas studies of adverse health impacts from folic acid unless you count uncorroborated anecdotes on alternative medicine websites. Indeed, it would seem the very obvious and substantial risks from folic acid deficiency are far greater than the very minor risks of too much folic acid.