Today I finally found out how to fix the path of the forums.
The name of the vocabulary is "Forums". To access it as expected in pathauto, you use [vocab-raw].
The result of [vocab-raw] is "forums" (all lowercase.)
Then, by default, pathauto adds the list of categories to the path. This is done using the [catpath-raw]. Say you have a forum named "Linux Stuff", [catpath-raw] will return "Linux Stuff" as is. This makes sense because paths on Linux are case sensitive (actually, it's the same thing with Apache wherever you are using it, although it's a