The article refers to silver pieces.. this is gold/electrum. .. anyways.. regardless of authenticity of otherwise, I will need to explore this more in depth.. there are lacking of sufficient references at the moment to derive a conclusive outcome. Best that I explore and consult with my source the next time...
If one knows the script is is usually still possible to see what the intended characters were supposed to be even if parts are missing because of wear or bad photo's. The OP specimen is not worn, but there are still pieces missing which should be present in the correct shape of the characters. Moreover, there are elements added to the characters which should not be there. This has nothing to do with technical limitations of the ancient makers of these coins. It looks like a very clumsy attempt to copy a Brahmi text. I truely wish this coin turns out to be genuine, but this major flaw has to be satisfactorily explained. Especially when this is a rare coin i would advise not to consult any dealer, but seek scientific support, for example by contacting the Thai National Museum in Bangkok ?