As soon as I get home and look up the relevant rule(s).

No, that isn't your point - if you were right it would have written as my last comment but you're obviously not because it's written the way it is.

The second sentence would have been simpler: You receive 1 food from the supply when you take the grain yourself.

You can clearly see that the answer is "no". As I explained, "even" implies that that extra grain is not just for when you take the action.

What are you challenging? The card is clear: "In addition" so it's on top of the payment, made even more clear with "even when you take the grain yourself" clarifying that this applies even when you take it and not another player.

Try playing Imperial 2030 where investing in other states/companies is part of standard play.

I have successfully mixed I and K but only with experienced players.

I guess they figure the big "E", "I" or "K" on each card is enough. Also, it's not unheard of to mix the decks - I like I & K together, e.g.

Although, I would add that when both players know the game well, even with the standard game a match can be played in 45 minutes (including setup time).