Do the library and Scholar Embassy interact at all?
We had two thoughts:
(1) Both the Library and Scholarship Embassy provide the same special ability (there's no advantage to having both).
(2) The Library card has a 'draw 2 extra cards' effect, so it can stack with the scholar embassy to give 'draw 6, keep 2'
Most of the text suggests the former... but clarifications about the market card with library ability suggests that the library building has a 'draw 2 more card than normal' effect that might be stackable.
"Both of these rules can be (partially) disabled by the Library and the Scholar Colony. Their special abilities allow you to exceed the hand size limit for a brief moment. Even with 6 cards in hand, you could still use the Librarian. If you do, you must reduce your hand size to 6 cards immediately afterward by discarding cards from hand unused.
The Library and the Scholar Colony also enhance the Librarian action for you: you get 4 cards from the draw pile, from which you may keep two, discarding the other two. Only after keeping cards, do you check your hand size."
"The Scholar Colony is all about Improvements. This is why the Embassy of the Scholar Colony assumes the function of the Library: whenever you draw Improvements, draw 4 and keep 2 of them"
"Is there any difference between the Scholar Colony at level I and the Library, apart from the fact that the Scholar Colony also lets me draw a card at the end of every year?
No. Both do exactly the same in regard to drawing and keeping cards"
The library building allows you to 'take 3, keep 1' with the library market card.
Editor at Lookout Games
The Scholar Embassy and Library do not stack - they both provide the same identical benefit.