Civil 3D objects are defined by Styles. A language pack does not automatically translate the text inside your styles.
If you already have Civil 3D installed in English and need to add Spanish capability: civil 3d language pack
There are three official methods to obtain and install a language pack. Avoid third-party "cracked" packs, as they often corrupt the C3D database environment. Civil 3D objects are defined by Styles
Civil 3D language packs work best when the Windows Display Language matches. If you run Spanish Civil 3D on an English Windows PC, the date and decimal separators (comma vs. period) may conflict with the calculation engine. Use Windows Language Settings to synchronize. civil 3d language pack