I like how they had the inserts upside down in the one photo...
As far as the "mold" goes, depends on how it penetrated the felt fibers. Looks nasty for sure & to have gone all the way thru the brim. For that money with complete case, it is worth a shot at stain removal...
I'd try naptha & a brush for sure. Maybe naptha & a good old fashioned spinning would help.