Great concept. I always like additional landscapes, especially for the single-expansion ones like Projects and Ways.
Ekklesia
$4 - Project
At the start of your turn, choose one: Exile the top card of your deck or discard a card you have in Exile.
Ekklesia is probably too strong (nerf suggestinos welcome).
Ekklesia doesn't seem overpowered so much as swingy, both based on the Kingdom and based on shuffle luck. Note that unlike Cathedral, it only looks at one card for something to get rid of instead of (usually) five.
It's swingy based on the Kingdom because it's a lot more powerful if there's a way to get good cards into Exile. With something like Camel Train, it lets you pseudo-trash a card a turn until your junk-to-useful ratio gets too low, then it lets you get your Exiled cards slightly faster. With no other Exilers, it still lets you pseudo-trash a card a turn until your junk-to-useful ratio gets too low, but then forces you to take a probably-useful card out of your deck for a turn every second turn, which probably makes it too weak.
It's also swingy based on shuffle luck because one player could successfully Exile junk several times in a row while the other gets unlucky and exiles good cards. I don't want to be the player who opens Silver-Ekklesia and then winds up Exiling the Silver on Turn 3 while my opponent who opened Ekklesia-Silver has successfully Exiled two junk cards. Deck-stackers like Courtyard won't usually help (barring edge cases like Prince of Courtyards) because you draw your new hand after the deck-stackers take effect and before Ekklesia triggers at the start of your next turn. While many official cards have this problem to some degree (I've had horror stories from both
Rabble and Noble Brigand), it's still something that should be minimized as much as possible, IMO.
As for a potential fix, maybe something like: "At the start of your turn, look at the top card of your deck. You may Exile it. If you don't, put it back and Exile a card from the Supply costing up to $4." This does remove the ability to let you un-Exile cards whose supply piles are empty (most notably Stockpile), and maybe that was part of the point of the card, but this change makes Ekklesia more consistently decent.