Could you store some of that data in the BP it self, and activate on overlap.
So when the character chooses what their bindings are, you set a Var for each in an array or just as. This is now “E” Var.
When the BP get spawned, and gets the “Key” Stoke VAR it needs, such as “Q”.
On begin overlap, you can access that VAR and input that in to your string.