*cough* Karl X Gustav *cough*
Although I admit I might have contributed to confusion with the mishmash of mentioning 3 regents in one post. If it's worthy of any note, the highest possible position (under the king) in the military would be Fältmarskalk, I think Field Marshal would be the best English translation but using the Swedish terms and names may add some charm to the army as a whole. Probably not worth investing in looking for a name among the real marshals during the Deluge period though, because there were literally more than half a dozen of them serving during the war - and the most famous (as far as I know) was a cruel bastard. So whether you just keep your own or whatever is irrelevant to me.
-General Sebastian Hische, Commander of his Majesty King Gustavus Adolphus of Sweden's armed forces.
-Field Marshal Sebastian Hische, Commander of Your Majesty(/His Majesty) Charles X Gustavus of Sweden's armed forces.
-Fältmarskalk Sebastian Hische, befälhavare av eders majestäts Karl X Gustav av Konungariket Sveriges väpnade styrkor.
(Switched it from His Majesty to Your Majesty because it's more formal, at least in Swedish
This is all just a big suggestion and I'm perfectly fine if you decide not to roll with it since I realise the complications that it might bring, despite the possible uniqueness. General also works well in Swedish since it has the exact same spelling and meaning
. (Albeit with a different pronunciation)
While you might not roll with the Swedish language, I think largely basing the names of the different regiments (or regemente
) on the different regions in Sweden as they did historically could also be a charmer. For example Dalregementet (Or Dalarnas Regemente for long) has already done this - based on Dalarna, a Swedish county.
Swedish rank names could also be extended from the Fältmarskalk to other ranks and if you're at all interested, I could fetch the different ranks and their roles and translations for you.