When you play a card from hidden, it gains several additional restrictions. The rules were somewhat unclear on this.

That’s not a question. But alright, let’s spell out the restrictions more clearly: A hidden unit must be played to that battlefield if able. If a hidden spell or a play effect of a hidden permanent chooses any targets, those targets must be chosen from among options at that battlefield, unless the ability explicitly restricts targeting in a way that makes this impossible. If a hidden spell or a play effect of a hidden permanent causes you to play a unit, you must choose to have that unit enter the board at that battlefield.