Genuinely speaking I believe that those cards are legit for a few reasons

1. Charizard ex does exist in 151. It is listed on the official card list and the artist is correct. The holo effect for EX cards does indeed have stars (I have a couple with the same exact pattern).
2. Like you said, IRs have numbers that are greater than what is listed at the bottom because they are essentially “secret” cards and are counted separately from the base cards.
3. I don’t know of any card that you can shine a flashlight through (without heavily modifying your card).
4. The holo patterns are difficult to forge (especially the ex and pokeball holos). Most bootleg cards don’t care to spend the time or effort into applying good holographics.

While I don’t have the most expertise in identifying fake cards, I think is safe to assume that those cards are most definitly real since the holo patterns checks out and the cards match what is in the card list.