The consensus when it comes to the NRA is that the Civilian NRA instructor certs and you should do your own "due diligence" when it comes to legal issues. If you hold a blue card, IE NRALE (law enforcement) cert, then you pretty much fall into ITAR restrictions. This is still a do your own "due diligence" situation, but you should pretty much go the DSP-83 route.
Since there is a myriad of instructor level certifications out there one should always be concerned. Another generalization is that if you train or have provided training to LE or Military, it is best to be on the side of caution. If you are current or former LE or Mil and now you provide training, you need to be cautious. If you have ever had a moniker of being recognized as a Subject Matter Expert by an agency, courts, or a recognized professional organization, or industry entity, you almost certainly can be held accountable by ITAR standards.
Many companies just flat out don't deal with Foreign Individuals. I have been to many private companies based courses that are restricted to either Mil or LE or both and many foreign entities often decide the issue isn't worthwhile on a small scale or individual basis, usually in regards to costs and red tape. It is easier to do a large foreign entity with a mobile cadre.
For my company, my course registration includes an acceptance policy of Credential and ITAR rules, plus requirements and recitals that all need to be sworn by the applicant. Many companies require a background that can be purchased online, kind of like drivers abstract, but a legal background from the state.