Unfortunately I do not believe what you are trying to do is possible using blueprints. You cannot access a variable using a string. You need a reference to that variable. I have two possible workarounds for you to try though:
1.) Make a structure containing an array of ints. In your bp, create an array of those structures. This used to not work, but the bug report is marked as “could not reproduce” so it may work now. (UE-11171)
2.) Combine your arrays into a single array and use indexes to mark boundaries.