Hello Anteevy,
You are able to get callbacks from FMOD when a marker is passed using the FMOD_STUDIO_EVENT_CALLBACK_TYPE and the FMOD_STUDIO_TIMELINE_MARKER_PROPERTIES API calls.
https://www.fmod.org/docs/content/generated/FMOD_STUDIO_EVENT_CALLBACK_TYPE.html
https://www.fmod.org/docs/content/generated/FMOD_STUDIO_TIMELINE_MARKER_PROPERTIES.html
There isn’t a way to get a list of markers from an event without playing it, but you can still use your game code to simply spawn the enemy when you get a callback from marker “A”.
I hope this helps.
Richard