ATJ Cylinder Head Washout: Causes & Repair

Hello!

Today, I had to remove the cylinder head (a common issue with AJM/ATJ engines, causing coolant to leak).
On the 2nd pot, it was clearly visible where there was a leak. After cleaning the cylinder head, I'm now wondering whether I should have it re-planed or not. It has slight corrosion, which can be felt with the fingernail, but it also already has a 3mm gasket. How should the corrosion be assessed?

Regards,

Matzepatze.

3B 4motion ATJ

Planning is actually not allowed, but in my experience, it's not critical up to 1/10mm. However, a thicker gasket is not used for this reason!