Visa Waiver/
The TSA and FAA have made it very strict on these items, if you are a Non US passport holder you need to have TSA clearance for flight training to include the following IR/Commercial/ an additional rating.
Attempting to enter on a Visa Waiver program is not the correct way and you are taking a huge risk at border control.
In addition before any simulator training can take place or actual flight training the TSA training has to be approved, the only exemption to this is ground school.
The Above rules also apply for Resident Green Card Holders, and holders of H1B visa,s the only exemption is that your are a USA Citizen.
I hope that this helps.
Best Regards