Regarding the topic,
The mechanic from the videos I posted before seems to be very experienced and he was literally shocked when he started welding the crack. The thickness of aluminum in that area was around 2mm. As an example, he was comparing and showing some Chinese brand cylinder head he found in his workshop, and the thickness of the aluminum edge there was about 7mm, which is approx 3,5 thicker.
Finally, he was highly disappointed with the way how Mazda designed the new cylinder head, specifically in saving the cost of aluminum in that area.
His advice was to not leave this particular engine downtime for a long period, as hydraulic cranks (the area where cracks appear)can possibly get jammed and cause significant stress when the engine is starting again after a long downtime.