Apart of need to priming sync demanding sound to load in audio cache “Loading behavior → Prime on load” The other way how to decrease audio latency is to decrease audio buffer size in UE → Project settings platform f.e. windows
In this case when I lower the value to unreasonable small amount for game engine I have latency between Gamethread audio call an sound actually plaing 21ms as shown in video. So yeah we are demanding 100% sync in pretty complex asynchronous software as UE engine is 