I have never heard of any baramundi stocking being done in the US, legal or illegal. I would imagine, if they had been stocked and took hold, it would be fairly well known.

There were two species of peacock bass stocked into south Florida legally by the Florida FWCC. Butterfly peacock bass have taken hold well in much of southern Florida. However, with the record cold this past winter brought, their northern limit has probably been shifted much further south than in previous years... The speckled peacock bass is the other species introduced, however it has not done well in south Florida.