16th Century Madonna & Child

Could be. I couldn't find any 1523 silver out there on NGC. it was all gold.

It looks like this Hungarian denar: https://en.numista.com/catalogue/pieces36848.html (and I think the year might be 1525).

This is the certification of Authenticity. This says it is from 1540 - 1600's

"Solid" is a weasel word without a technical meaning, except in the sense of "not hollow". It implies purity, without actually stating it. An 8k gold ring can be marketed as "solid gold", and they wouldn't be lying; the ring is solid, not hollow. But it's still only 8k, not 24k.

I'd also agree that it's definitely from the 1520s, and that therefore the "certificate of authenticity" is wrong in that respect.

I would assume the mass-marketeer dealer who manufactured the COA packaging bought a bulk lot of Hungarian denars, and most of them were indeed Ferdinand I, so put them all into the same COA packaging without checking each individual coin too closely.

Postal Commemorative Society, now known as PCS Stamps and Coins, is indeed a mass-market dealership and is still in operation - just looking at their website, it seems to me their target market is not the skilled numismatist who knows the market and current pricing, but rather the casual collector who just want to buy an old coin or two. All of their coins are sold in pretty custom-made wrappers like this, and these wrappers and certificates don't come cheap. Whoever originally bought it from PCS, probably paid way over the market value for a Hungarian denar at the time.