At this time nothing smaller than a 28 gun ship was ever called a 'frigate', even 28 gun ships were rare and not used as such. So, not a frigate, never a frigate.

All sixth-rates had a 'post' or full captain in command. That is why the ones too small to be called a frigate were called 'post ships'. The term corvette (borrowed from the French) was later used for these ships.

The armaament you give is wrong too. Although designed for 9 pounder guns (another 'clue', frigates don't have 9 pounders) by 1815 she had been re-armed with carronades on the upper deck (if indeed she ever carried 9 pounders).

These Banterer Class sixth rates were built with a quarterdeck which made them look like a frigate, but at 537 tons were about half the burden of a contemporary 'heavy' frigate and about a third of Constitution's.

Sorry Walrus old mate, but this is my 'specialist subject'.

Les