You can either control the scale/position in the Birth Terrain operator, or add a Terrain Transform operator at the end of your event and control the scale/offset in there.
Many terrain parameters are sensitive to scene scale and are tuned to default scale settings, so the latter option (Terrain Transform) will ultimately be more convenient than the former, so you don't have to retune all your other settings if you change the terrain scale again. By doing Terrain Transform at the end you treat scale as a post-effect that won't affect any other settings.
Many terrain parameters are sensitive to scene scale and are tuned to default scale settings, so the latter option (Terrain Transform) will ultimately be more convenient than the former, so you don't have to retune all your other settings if you change the terrain scale again. By doing Terrain Transform at the end you treat scale as a post-effect that won't affect any other settings.