Hi,
It turns out that “Auto activate” on the particle system is a special case. All other properties should work as you expect - you should be able to set any property value on a spawnable (even if you’re not keyframing it) and when it despawns and respawns, the property value should come back the way you set it.
For “Auto activate”, we intentionally disable it because when it is enabled, the particle system will fire when it is spawned. In our internal uses, this wasn’t desired so instead we encouraged explicitly keyframing auto activate if you want that behavior.