Are there cases where an Enchantment Aura effect remains on a creature when it is returned to owners hand?
Comprehensive rules 400.7:

An object that moves from one zone to another becomes a new object with no memory of, or relation to, its previous existence. There are nine exceptions to this rule [...]

and none of the exceptions apply here. Therefore the object in your hand is the card Lorescale Coatl, and if you successfully cast it then it will be a &quot;regular&quot; Lorescale Coatl with its normal abilities.
Related to this, Frogify itself will go into its owner's graveyard.