Another question asked and answered by Thai embassy in Paris.
Asked: Can I verify if a school is officially allowed to participate in soft power scheme.
Answer: "The school needs to be officially registered."
Follow up question: How can I verify if the school is officially registered?
Answer: "You have to check with those schools directly. The embassy do not have the information. "
So in conclusion: There is no way to verify a school, but at the same time the embassy can turn down your application if they deem the school not officially registered?