Yes, it can be handled at design-time.
What you’ll want to do is create a single parent event that plays your music, as well as all other audio you want to sync with the music, and a number of other events for all of your individual synced audio The synced audio will muted in the parent event, and instead will be sent to different events using Transceiver effects, where it can be spatialized.
Here’s a quick mockup of the parent event, playing two SFX tracks (a single looped instrument vs multiple instruments) alongside a music track:
I have placed my synced audio assets on separate audio tracks from the music, have set their faders to -∞ so they don’t produce any audio. Then, pre-fader, I’ve used a Transceiver effect set to transmit the signal from these tracks elsewhere. Each SFX track is sending to a different Transceiver channel.
Then, I’ve created a separate event with a Tranceiver set to “receive”, and placed a Spatializer on the event so the synced audio that it receives can be spatialized:
Instances of this event will all produce the same audio being played in sync by the parent event, but can all be spatialized individually.
The only other thing to note is that using a transceiver introduces a single mixer block’s worth of latency between the source and destination - if you’re finding that this makes your audio a little too unsynced for your liking, you can also use a transceiver for the music track so they’re all at the same latency.
Let me know if you have any other questions.