Hey,
First of all, since you’re still on 4.13, you might be suffering from a bug in Blackboard editor, that results in newly added keys being configured as “shared” keys, which usually is not what you want. Go to your BB asset and make sure your keys are not “synced”.
Regarding EBTNodeResult yeah, you’re not using it right. When you return EBTNodeResult::Succeeded the task ends it activity and BT proceeds to the next task, so it’s not what you want to return from UBTTask_Cooldown::ExecuteTask. Look at how UBTTask_Wait does its thing.
Let me know if applying these two nuggets of knowledge to your case didn’t help.
Cheers,
–mieszko