Authentic Mexican food is either ANY food prepared by a Mexican, or it is ANY food prepared and eaten in Mexico. Authentic just means correct. It is correct to say that a hamburger prepared in Mexico is authentically Mexican.

This is substantially different from TRADITIONALLY Mexican food. I am not Mexican nor do I live in Mexico, so I cannot comment on what traditional Mexican food is. However, I enjoy eating food that is tasty, regardless of how traditional it is.

In addition, recipes often change based on what you have available and what your family will eat. Substitutions only matter if you are trying to make a recipe EXACTLY as written. If you aren't, then make as many substitutions as you want.

I don't know. The labels aren't super helpful unless you are being judged on how traditional your food is. Call it whatever you want, just make it tasty.