You can take it as a given that everything we do in the future will be on both Steam and GOG. If they DON'T decide to take something, you'll be sure to hear about it. 
Is it perhaps the case that your 'problem', or part of it, is you sell titles below GOG's lowest price? GOG's pricing starts at $5.99 (the $4.99 price was a trial), which means to sell The Shivah: Kosher Edition and perhaps Puzzle Bots on GOG would require bumping the price up by at least $1? Obviously $1 isn't a big deal, but it does look strange to have a game at $5.99 on one store and $4.99 elsewhere. The only way around it I can think of would be a sort-of combo pack, with The Shivah, Puzzle Bots and something else in one package for, say, $10. But again that's not a perfect solution.
So is it safe to assume that one reason these titles might not be on GOG - aside from GOG perhaps rejecting them for now, which they've been known to do - is that you price below GOG's lowest boundary?
(Actually, may have spotted a flaw in my theory or a workaround. The Shivah: Kosher Edition + OST = $6 value at least, but generally OST inclusion is considered 'gratis')
Edit/P.S.: Talking of the OST, any plans to release the new one?