[Callback request] MC_[PRE/POST]_NPC_FIRE_PROJECTILES
Projectiles spawned by NPCs are difficult to work with due to not having a spawner entity set, this would make it much more convenient to remove or change properties of projectiles. Maybe even be able to return a modified projectile param object?
Anything spawned by EntityNPC:FireProjectiles() has its SpawnerEntity set so this just isn't true. Also, Repentogon adds FireProjectilesEx which returns the projectile(s) spawned so adding custom properties to your own projectiles is easy with that.
Being able to change ProjectileParams may still be useful however but its a bit niche outside of stuff like recoloring projectiles of vanilla enemies for custom stages.
You are correct about SpawnerEntity being set, apologies for the confusion