see below

"The court held that the fact that the law does not specifically mention Directors is not to be interpreted as a negative arrangement, rather it is a lacuna which must be addressed in light of the legislative intent to encourage creators to create cultural works."
http://www.tglaw.co.il/en/article.php?id=41

"On this view it is plausible that Article 5(2)(a) of the Optional Protocol (the lis alibi pendens clause) did not create a negative arrangement as to the application of the res judicata rule, but rather failed to address the question of finality. Hence, the res judicata rule may be relied upon to fill this lacuna"
http://www.oxfordscholarship.com/view/10.1093/acprof:oso/978...

These two terms can be found in proximity quite a lot, however you should note that all the hits with these two terms are ultimately related to or Israeli in origin (or written by an Israeli). So whilst I'm fully behind "Lacuna/Non liquet" I'm taking "negative arrangment" with a pinch of salt and I would suggest you do too. I include it here only to demonstrate that it has been translated this way many times before (in legal journals and other official documents if that helps lend weight to it?).

P.S you really should open another question for the 2nd term though, maybe someone will uncover something more.