Valve Cover Damage

[biostudent]

First let me say thanks for all the help so far.

I came across this while I was getting ready to do my valve adjustments. I cleaned the valve cover ( I plan on painting or polishing it).

Apparently there is some pretty noticeable damage. I just wanted to see if I should be very worried or if this was just a thing that happens sometimes?

Here's the pics.

Also, is that black tar suppose to be there (pic 4), it looks to be a sealant or something.