Would Stylized Spell meet the requirements for adding the +2 for that ability? And if not are there any other ways to add to this plus?
Covert Spells (Su): An enchanting courtesan can cast divination and enchantment spells covertly. Upon doing so, the enchanting courtesan must attempt a Bluff check, as well as a Sleight of Hand check if the spell has somatic, material, or focus components. Observers do not notice that a spell has been cast unless they succeed at both a Sense Motive check opposing the courtesan’s Bluff check and a Perception check opposing the courtesan’s Sleight of Hand check (if any). If the enchanting courtesan has another ability that allows spells to be hidden in a similar fashion, he gains a +2 bonus on these checks. Casting the spell does not provoke attacks of opportunity from foes unaware of the spellcasting.
I think 'hidden in a similar fashion' would mean conceal spell or cunning caster or spellsong, something which allows you to hide the fact that you're casting a spell at all. Not something which merely hides which spell you're casting like stylized spell does.