You can ignore the outer water jacket groove.
I've never seen a failure on the outside one unless we're talking severe corrosion problem or extreme overheating.
The majority of the punishment is done to the inner water jacket since it has to seal combustion!
More specifically, the area from 12 o'clock to 9 o'clock (or vice versa, depending on how you're looking at the housing) which is the area where you start the ignition cycle through the combustion cycle to the end of the exhaust cycle is most important.
Sometimes it's very hard to tell from just pics on where the coolant leak came from.
It's almost necessary to be there - in person - to get a good idea of what is going on.
I tried to the best job just by the pics you posted...
Another question...
Assumed you did torque the engine down in the specified order...
How much torque did you tighten the tension bolts down to?
What kinda torque wrench?
-Ted