Die Taverne von Andor

Is it wrong to combine grey and golden decks of events for Legend 3?

Yes, you only use one deck, golden or silver.

Yes, i know, but I want to combine it for more randomness) Can it hurt the game?

Nothing is forbidden, it is your game, play it any way you want.
I see a small quirk, silver cards are mostly better for the heroes, so if you see a silver card on top of the deck, you might be more inclined to take it. Actually it will become less random, as you see which type of card comes next.

In that case I would draw from the underside of the deck.

11 silver cards: 6 good and 5 bad.

Silver+golden: 45 cards: 23 good and 22 - bad.

It's almost 1:1)) Also I dont remember each card, silver or golden - no difference))