Here are some ranks I found on the TaleWorlds forum.
Foot
Oberst [Colonel]
Obsertleutnant [Lieutenant Colonel]
Major [Major]
Hauptmann/Capitaine [Captain]
Oberleutnant/Premierlieutenant [First Lieutenant]
Leutnant/Secondlieutenant [Second Lieutenant]
Fähnrich [Ensign/Colour Sergeant]
Feldwebel [Sergeant]
Unteroffizier [Corporal]
Gefreiter [Lance Corporal]
Musketier/Füsilier/Grenadier/Gemeiner (Depending on troopkind) [Private]
Skirmisher
Oberst [Colonel]
Obsertleutnant [Lieutenant Colonel]
Major [Major]
Hauptmann/Capitaine [Captain]
Oberleutnant/Premierlieutenant [First Lieutenant]
Leutnant/Secondlieutenant [Second Lieutenant]
Fähnrich [Ensign/Colour Sergeant]
Feldwebel [Sergeant]
Unteroffizier [Corporal]
Gefreiter [Lance Corporal]
Jäger [Private]
Cavalry
Oberst [Colonel]
Oberstleutnant [Lieutenant Colonel]
Major [Major]
Rittmeister [Captain]
Oberleutnant/Premierlieutenant [First Lieutenant]
Leutnant/Secondelieutenant [Second Lieutenant]
Fähnrich/Kornett [Ensign/Colourseargent]
Wachtmeister [Seargent]
Unteroffizier/Corporal [Corporal]
Gefreiter [Lance Corporal]
Reiter [Private]
Artillery
Oberst [Colonel]
Oberstleutnant [Lieutenant Colonel]
Feuerwerksmeister [Major]
Feuerwerkshauptmann/Rittmeister [Captain]
Oberfeuerwerksleutnant/Premierlieutenant [First Lieutenant]
Feruerwerksleutnant/Secondelieutenant [Second Lieutenant]
Stückjunker [Ensign/Colourseargent]
Oberfeuerwerker/ [Seargent]
Unteroffizier/Corporal [Corporal]
Bombardier [Lance Corporal]
Kanonier [Private]
Source: forums.taleworlds.com/index.php?topic=239929.0