Unreduced caapi tastes quite ok, I can imagine someone sayings its 'good'. Reduced caapi done on high fire tastes horrible, very very bitter. Reduced caapi done on low fire/simmering tastes strong but manageable. Over-reduced caapi tastes worse.
Adding acid to it makes it taste worse, I suggest brewing your aya without acid, 4x boils (no need for so many hours), reduce on low fire to 50-100ml per dose (more = better taste but more to swallow, less = stronger taste but can drink in a sip faster)... Dont throw the caapi out, then do a long multiple-day acid soak followed by boiling, doing this once or twice and ideally blending or freezing the bark, specially if it very very finely shredded to begin with. With this, extract the alkaloids. That way you have most/all alkaloids and yet you drink only the nicer tasting aya.
Caapi made in the above mentioned way tastes woody and somewhat bitter but not too much, quite decent imo.
Maybe it's also possible different caapi varieties have differing tastes? im not sure...