re-read the manual... tl;dr, is it possible for a trigger to both run a script and play a sound outside of that script's run window?
afaik sounds in scripts during map runtime aren't broken they just aren't a feature at all.
are you saying that you have a trigger run a script and it is playing a sound and it's working, just getting cut off?
if that is the case, try adding
timeout #
after the line executing the sound, and replace the # with the number of seconds that your sound is. this should theoretically halt the execution of the next line in the script the specified number of seconds, allowing the sound to finish playing.
to make a sound a play without a script at all, you can specify the sound instead of specifying a script file