1784 Spanish 2 Reale . Is It Authentic?

The coin does look genuine in my opinion.

It is a peninsular issue struck in Madrid Spain. The silver content (0.833) was actually established to make these coins worth less than their face value. These were therefore tokens that rarely left the Spanish homeland. Spain was on a war footing and the government did not want silver to be exported.

The wear level (AG in my opinion) makes the coin of very limited interest as a numismatic item. Value is based on how you feel about the coin as an historic item.