I recently checked the time differences between the scenes in Not A Hero where Chris gets the mask after Lucas kills his partner. In the Japanese (I assume) version of the game, it is about 8-9 seconds faster than the US version, thus the "in-game timer" is much shorter for the Japanese version vs. the American version. Are we taking this time into consideration, or does the Japanese version have the upper hand in the Not A Hero speedrun?

Just like in the main game, the Not a Hero DLC does have a time save for using the Japanese CERO D and CERO Z versions. The CERO D version saving more time than CERO Z. I posted a video showing the time differences for this in the RE7 discord shortly after it released, I’ll link it here now too.

Shortly after we realized that the CERO D version of the game saved time in the early days there was discussion about how to handle it. Ultimately, the CERO D version does save time and is the version that most of the top console runners use since it is accessible by import outside of Japan.