since it updated, jack said he was going to get revenge on lord english and for the casino. why would he want revenge for the casino/lord english?

From Spade Slick’s original introduction back in the intermission:

A rival gang known as THE FELTrecently knocked over one of your favorite casinos. Your long quest of revenge has finally taken you through the front door of the mansion belonging to their loathsome boss, LORD ENGLISH.