Tried the following experiments on the training dummy. The background for these results is I am trying to trigger Rip Blood on cursed enemies via Crimson Enlightenment, while having the Acute Affliction node to make the curse end early. I was mostly using Soul Feast (which can hit up to 6 extra times) as the trigger.
Control experiment: I was able to trigger Rip Blood immediately by casting Soul Feast once when Soul Feast applied 4 or more hits. This result is as expected.
However…
Bug 1: If your first cast of Soul Feast does less than 4 hits (hence no trigger of Rip Blood), casting Soul Feast a second time and dealing enough hits to being the total to 4+ will NOT make the Rip Blood trigger. In addition the target seems no longer to be cursed because a 3rd cast of Soul Feast returned no shards. And after 8 seconds there will be no trigger of Rip Blood. Problem seems specific to Soul Feast as the Rip Blood triggers work as expected with other hit skills. Except for one…
Bug 2: Rip Blood never once triggered early with Wandering Spirits with Spectral Putrescence, hitting the dummy, despite the tooltip for this node making it clear that the spirits “hit” with this ranged attack (it applies poison “on hit” after all). Acute Affliction tooltip does not state that the 4 hits that should end the curse and trigger Rip Blood need to be applied by me, so this should work. I also assume in multiplayer, the hits dealt by other players should trigger it but obviously I cannot test that.