This is a fixed version of the file here: http://simplici7y.com/items/marathon-red-addenda
To install, simply drop the .mml file into the Scripts folder in the RED scenario folder.
The idea behind this MML is to restore some of RED's appearance which was not preserved in the old Aleph One port, which as of this writing was last modified in 2011. Note that if you're playing a newer RED port then this file may not be necessary.
I make no guarantees that this does correctly restore aspects of RED, as I have not played the original scenario files. This is merely a correction of syntax errors in the MML file. I have also removed the fog that was added in that MML as it was not a part of RED originally.
The MML file will actually load in Aleph One now.