OK, maybe the title is misleading. The idea is: During Christmas, Halloween and CNY, the 3 pirates mentioned above regain stats as per previously. During the non-festive seasons, they end up like this: EG. Ching Shih Lvl 1 2000 gold (correct if i'm wrong) BECOMES 5000 Gold + 5000 Grog + 100 EP + 50 BP + 5 gems Oh yes, and a waiting time between recruits is.... 1 day. If you want to use her again, you have to pay the gem duty that's worth 1 day. This way, people won't whine about Ching being gone etc. and people would be restricted to 1 raid, therefore not overpowering them. Please comment.
Frankenbrute and Santa will only ever be available on a seasonal basis. As for Ching Shih, well... Yes. Quite.
What might be more reasonable is: There should always be (at least) 1 seasonal/event/legendary/bunny-hat-wearing pirate available. When one season ends, it is replaced with a new one that update; no periods without one available.