Is it possible to add a new language via a mod?

[Alter Native]

I translated the game to German (partially by hand, partially via an AI translator and correcting afterwards) and right now the game is completely translated and playable in German.
However I'm overwriting the Spanish translation. Is it possible to add a new language via a mod?
Meaning I'm looking for a way to add a new flag in the bottom right of the main menu.

A second problem is, that it doesn't seem to be possible to overwrite any of the files in
Campaigns\_1861 Blue and Gray\Scripts\Events via a mod?
Only when overwriting the Spanish files directly does it work.

[Hortense]

Document/My Games/Stratégic Command - American Civil War/Language
change EN or ES to FR or DE according to the desired language

[Alter Native]

Thanks for the reply, but that was not my question.

[Hortense]

O. I don't have a mod to offer you, but this method avoids overwriting other Spanish or English files. you must first copy the files in the folders concerned by your translation. I did it with my own translation and it works.