Urgh, my page refreshed and my response is gone. Gonna retype it all.
Based on the content of your quote (of what I said), I don't think you saw the edit I made to my original reply.
Basically yeah, I think it's a result of cheat codes from lazy code makers.
They found a byte that works when written to a hex address, and rather than testing to find the intended bit, they just released it as is.
Injected wonder cards show up in the album viewer.
Here's an example, that I literally just did to show you:
As such, it cannot be used to verify whether an event was injected or not.
Yes, cheat codes may or may not have the card (depending on what cheat codes a hypothetical person uses), but wonder card injection definitely shows the card.
(tangent: no idea why you're calling it a voucher)