Corrosion at top/front of engine
 

Hi everyone, been lurking for a while. Have a 2002 Boxster with 46k miles and my mechanic discovered corrosion/coolant leak on the top/front of the engine, right below the power steering pump. The hypothesis is that there is a rectangular coolant duct in the engine casing right below this point and that the gasket has failed, resulting in coolant seeping out. It could also be loose casing bolts at that location. It doesn't appear to be leaking currently (coolant level is fine), so the corrosion may have sealed it up. I am attaching photos and diagrams of the location.

Has anyone seen this failure before (my mechanic hasn't seen this before)? Does it make sense to clean up the corrosion area? Maybe replace the casing bolts there? My dad things I should use jbweld to seal that spot up as well. Thoughts or ideas?
http://986forum.com/forums/uploads02...1582818675.jpg
http://986forum.com/forums/uploads02...1582818701.jpg
http://986forum.com/forums/uploads02...1582818714.jpg

I've seen lots of motors and I've never seen that happen before