If you can't spawn it may be down to a coding issue (such as spawns or flags not named correctly or named or numbered the same), could also be a dodgy object spawner (vehicle or something) or an autocontroller not tied to a flag/team. Could be a number or combination of things so difficult to pinpoint unless you go in to the code, or fire it up in the editor and check and double check everything.

As for terragen, never used it. Have you looked on the bfeditor.org forums? They usually have tuts for just about every program used with Battlefield.

Bite my shiny metal Tie Fighter!