As stated, I was unable to test on 4.14 because the project you provided was created in 4.15, at least as far as I understand, and there’s no way to roll back. When I tested in 4.14 I was unable to reproduce the issue by playing a sound based on an event such as key press.
As far as the steps I took, I booted up the project, played in a new window with 2 players, set net pktlag to 1000, and then ran to trigger the sound. Then, after I ran, I quickly switched over to the Server or Client (depending on which did the running) and I was able to hear the sounds play as the characters moved.
I didn’t change any settings or anything inside of the project you provided, just to be clear.
Is there a step that I’m missing somewhere in your project?