It’s generally not allowed under international law to target civilians. Civilians getting killed when military objectives are targeted are legal. Proportionally and necessity come into play here.

This is true but it’s only fine if you target “fighters” according to the blog. So it depends on the details of who these people exactly were, just being in Hezbollah is not enough. As you said it’s whether it’s truly proportional and necessary.

And for the targeting thing I think the main issue is whether it was possible in this case to control or even minimize the collateral damage. Since you don’t really know the situation you’re setting a bomb off in:

The targeting law concern will be more likely to centre on whether adequate consideration was given to the incidental injury and damage to be expected from these explosions, given, as is assumed to be the case, that those planning and conducting the operation cannot have known the circumstances that would pertain where each of the large number of explosions took place.

As you said, don’t confuse targeting with who gets hurt at the end. It didn’t come out too bad (by Israel’s standards at least) but that doesn’t mean they exercised the due care in how they did it, legally.

Compare that go Gaza, which has about 2 to 3 civilians per combatant killed.

Would be interested to see where you got those numbers