Please dont use IPA for harmalas, it sucks big time! Just try it out yourself, with pure alkaloids. Even freebase (which are generally much more soluble in alcohols than salts) are poorly soluble in IPA, so the natural salt form in caapi must be only slightly soluble in it. Sure you might get some psychoactive product, but dont throw that caapi away, extract it with water afterwards and you'll most likely get a significant amount of alkaloids. Ethanol is better than IPA for this, but I would still go for water