I just noticed that the PACG product page for Wrath of the Righteous lists the card guild adventures, bringing the number of products to 18, while the Skull and Shackles page does not list those products.
I am not sure which version is desired, but the Rise of the Runelords page also seems top list them, so Skull and Shackles seems the odd one out.
Thank you for the heads up! I'll add revising this to my to-do list. We could have a bit more uniform distinctions in these areas for sure.