If you are using a legitimate copy on a launcher, the process is streamlined:

For newer repacks (like those from DODI or FitGirl), you can often switch languages by editing a configuration file without downloading extra packs if the data was included in the repack. : Navigate to ...\sp23\steam_settings . File : Open configs.user with a text editor.

If it's missing, you may need to download and copy the entire english folder from a verified community source .