I might be wrong but I think you are asking for a way to get the damage for a specific Spell Actor.
From what you shared I get you have an InstantSpell class with a struct containing all its defining stats. Doing what you did will get the stats of the colliding specific Spell (say FireSpell).
If FireSpell inherits the struct containing the stats (say SpellStats) from InstantSpell, and assuming you set the stats for FireSpell during init of FireSpell object, what you did in your screenshot will always return the stats of the instance of FireSpell currently colliding with your Rock Actor.
A good way to store all the specific stats per spell would be a DataTable, where you could just list all the stats with for specific spells, indexing them with a SpellID (wich needs to be a variable of the InstantSpell class). Doing this you will simply have to get the data relative to your currently colliding Spell ID from the DataTable whenever you need so (and you can encapsulate this logic in a function in InstantSpell, and just use that to get wathever stat you may need for your spell)
Hope this helps