Be advised that for current build of L4D2 & workshop, you need to use the following command to load fonts from console:

alias reloadfont "mat_setvideomode 1920 1080 1; mat_setvideomode 1920 1080 0"

-you need to replace "1920 1080" with your l4d2 resolution and then add it to your autoexec.cfg in /cfg folder.
If you don't have an autoexec.cfg in
steam\steamapps\common\left 4 dead 2\left4dead2\cfg\
you can create a .txt file and rename it to autoexec.cfg, then edit it with any text editor like notepad.
More on mat_setvideomode here:
http://pastebin.com/YEiMzJT0

After the command is added to autoexec / aliased , you'll be able to execute it from console (by typing "reloadfont" )
in order to load / activate the font mod.

You can also use the reloadfont button feature of my "Game Menu" mod for that matter.

P.S.
As you know, workshop addons also take time to initialize, so you may have to wait a few secs, depending on your connection, before executing those commands.