So long story short: I gave my monster the vacumn spell gem, I tried sucking up a few temporary traits, but despite being showned as acquired (temporarily) when I use inspect on it, the effects don’t activate. sounds like a bug to me…
edit: found a few that worked, but others still don’t…i.e. azure dream’s boss fight, crypt bat, one of the valkyries don’t work, but pandamonium queen’s trait does.