TL;DR - Play in Japanese until the menu before the Magic Beast fight after Nefarious Saints in Disc 4. Switch to German. Assuming fast menus, you'll save a few seconds by switching.

You can switch languages on the fly in Lost Odyssey. There are 6 dubs in total: English, Japanese, German, French, Italian and Korean. Korean is untested.

As a whole, Japanese is ~17 seconds faster than the next fastest language, French. Switch to German at the end and you get ~21 seconds of time save over English.

I suggest changing the language before Grand Staff Magic Beast as you need to change formation anyways.

https://docs.google.com/spreadsheets/d/1XpurJTXzdJKSMl0HJgMf9ZKJtHGojNmJVmSiJQVjBTI/edit?usp=sharing