How do I set up triggers that use a LoopIndex?

Here's what I'm trying to do. I'm making a slot selection screen for my game and displaying 3 files. I'm using LocalStorage to check for metadata about each slot, using item names e.g. "Save1", "Save2", "Save3". I want to trigger actions when the item is missing (which is a LocalStorage trigger) for any of these items. The LocalStorage "On item missing" takes the name of the key, for which I want to use something like "Save" & LoopIndex, however LoopIndex isn't defined at that time, so it never fires.

How can I generalize the event here, i.e. without hardcoding events to check for each slot - what if I wanted 100 slots?

For now I'm using a workaround which it to use "Get all key names" (since I'm only using LocalStorage for these keys) and comparing the keys returned and processing them that way, like so:

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