I just demonstrated that it’s not wrong. It’s a perfectly proper use of the English language, which is why it appeared in the paper I cited.
Show me something that demonstrates that “Indianan” is not permitted to be used.
Again, it’s Culture; not English.
It’s the official name. That’s all you need to know.
For your use, it would be an “unofficial” use per definition of the word.
-Which would mean “not formal”
-Which would mean “not proper”.
Therefore, it’s not proper to use the word ‘Indianan’.