Well I don't find any TGL lines in the plugin. I'm assuming your referring to the DJEnterprise.py plugin in the Custom/Ships/ folder. Usually I'm able to overcome this problem by changing the abbrev to the name of the stock ship i'm replacing. For example, when I replaced the stock ambassador with another ship, I changed the abbrev to ambassador and imputed my own description. When I start the game, the new ship description appears. I tried to doing the same for the galaxy class, but when I do, the ship appears ingame with the stock nebula-class icon in the tactical interface!