Finally got a chance to look at it.  It's a CS:S bug - ClientScheme.res is missing a font specification.  If you add this to the Fonts section, it displays white text:

        CenterPrintText
        {
            "1"
            {
                "name"        "Trebuchet MS"
                "tall"        "24"
                "weight"    "900"
                "range"        "0x0000 0x007F"    //    Basic Latin
                "antialias" "1"
                "additive"    "1"
            }
        }

I'm going to check the fix in, and I'll try to get it into one of the next releases.  In the meantime, at least you can test with this fix on your own machine.

-Matt