I've bought Pathfinder Adventures on Steam when it was released. Owned the Android version for some time already, so I've synced my accounts with Android one being the main account. I then redeemed Pathfinder Ambassador rewards on Steam, and everything seemed to be synced perfectly - parties, progress, purchases.
The only thing not working properly is the "Rise of the Goblins" campaign. In my Android account it's shown as not bought (price is shown in store, "Buy" button is white). Yet I have access to Goblin skins and characters - same as in my Steam account. I can even start a "Rise of the Goblins" campaign - but it won't sync between accounts.
Valeros's Tale, bought through Steam, appears as "bought" on Android too - and this adventures syncs normally.