I feel that's more of a localization issue rather than a story issue though, since they'd all just be Drautos Shogun, Cor Shogun, Glauca Shogun and Ravus Shogun when referred to in Japanese, rather than "Captain Drautos", "Marshal Cor", "General Glauca", "High Commander Ravus" as they are in the English localization. Specifically regarding "General Glauca" though, IIRC only Regis and Luna directly refer to him by that title in the movie, I don't recall anyone else mentioning the name "Glauca" or his military title in the movie, so that might have something to do with that inconsistency, or it could just be they wanted to sound more "flowery" in the loc of the game and used High Commander instead of General.
I don't know when they changed these like that though because I remember an old ATR where the official English subtitles mentioned "General Cor" when they were talking about him, and I always liked the sound of "General Cor" better than "Marshal Cor", even though technically they mean the same thing.
On that note Aranea is called "Aranea Junshou" which means both Commodore or Brigadier General in Japanese, while called "Commodore Aranea" in English.