I have fought Shoal yesterday. Could you make nereids a touch less determined to kiss charmed targets?
She is a tad harder now, isn't she? But the exhibited behaviour is in-line with PnP and I'd rather not alter it for convenience's sake.
However, a few things should be noted. First, a Nereid can't charm/kiss female characters, so sending Imoen/Jaheira/Dynaheir/Branwen... etc. after her will make the battle a lot easier. Likewise, sending some conjured/charmed animals to fight her (or basically anything with GENERAL != HUMANOID && GENDER != MALE) will have the same effect. Secondly, the Beguiling Aura can't affect Blinded characters so, in a pinch, you can blind your best male fighter and send him right in. Sure, he will have a huge THAC0 penalty, but at least he won't get charmed/kissed anytime soon. Lastly, if you can afford them, Potions of Clarity will keep your male characters completely safe.