According to the KL consulate, ALL Thai education visas now require a criminal record check. (Edit: added "according... consulate)
The downloadable form states that a criminal record check is only required for a degree program; that is not correct.
I drove 300 km to KL because the Thai consulate in Singapore claims not to process education visas. (Edit: Singapore only processes applications for degree programs.)
The attendant at the front gate of the Thai consulate in KL who checked my papers stated no criminal check is required; he is wrong.
The Thai attendant who processes all forms and makes the actual decisions says that a criminal record check is required as of one week ago. When I asked for clarification, he said from the Malaysian police. (I don't know if it was a factor, but I'm a Canadian who has lived in Malaysia for several years).
We were told to get the check from the police station a few hundred meters away from the consulate; that is not correct. That police station told us the check must be done at the federal police headquarters (10 km away); that is not correct.
The federal police headquarters in KL told us we must go to Putrajaya (25 km away) or do the form online. The online form includes a long list of requirements, including a letter from the embassy of your home country. Processing the form and providing a criminal record check takes 1-2 months.
I'm still navigating the bureaucracy and don't yet have a complete solution, but will likely have my plans delayed by several months because of this new requirement.
If you're applying for a Thai education visa right now, expect a high level of misinformation from the Thai consulate, the requirement for a criminal record check, and serious delays in processing time.
TLDR : Answer Summary
The Thai consulate in Kuala Lumpur currently requires all applicants for education visas to provide a criminal record check, contrary to previous information. This requirement has led to confusion and delays, with applicants directed to various police stations for the checks, often facing misinformation. The processing of the criminal record check may take 1-2 months, which could significantly delay visa applications. While this requirement seems specific to the Kuala Lumpur consulate, it is not uniformly applied across other Thai consulates in Southeast Asia.