So, I understand that on the surface, many of these are legal. Often times though, when we start applying them, we have to do things to get the person to tap that might start making them illegal.
The Kimura if not anchored properly, can be pushed real high up and sort of turn into a hammerlock or something. When it's like that, it's attacking the shoulder, not the elbow.
The D'arce is by all accounts, an arm triangle choke. The problem is, when you dump someone on their side and start rotating around to finish it, if you put your hips into the motion, it starts to put the same torque on their neck as a guillotine would.
I'm not really sure about the omopolata and those sorts of techniques, because I've never seen anyone successfully apply it in a tournament.