So I don't know much about modding but I tried to do this myself because I really wanted this. Basically there is a .archive folder for English VO audio that can be unbundled with CP2077 tools. So I thought maybe if I downloaded the English VO .archive and the Japanese VO .archive, I could unbundle, copy over V's JA voice lines to the English archive, rebundle, and mod it in. Quick in and out adventure. So I went inside the JA /vo/ folder in the archive and just copied over anything that started with "v_" into the EN one, overwriting the EN ones. I figured it was a good starting point at least, see if it made a difference. Rebundled and applied to the patch folder. Whenever I started a new game, it crashed right before dialogue started. I probably did something very wrong but am unable to figure out exactly what, but my hopes are low.