The translation team had a distinct advantage: the script for Dynasty Warriors 7 already existed in English from the PS3/Xbox 360 release.
This isn't a rough Google Translate job. The community has labeled this a patch, and it lives up to the name. shin sangoku musou 6 special english patch high quality
using texture replacement via emulators like PPSSPP. Full story translation is generally not available for the PSP port. Undub Patches Unlocking the Epic Experience: Shin Sangoku Musou 6