Hi I'm a pretty new runner for this game, planning to upload my first run soon, but I didn't record my PB run so gonna wait til I record a new one. Something I wanted to ask is that I noticed many non-japanese runners use the japanese version of the game for their runs. Is there any specific reason for this?

No one answered so I'll try. I don't think there's any good reason. Just using the version that the record holder has used since 2020 just in case it is faster.

In Super Bomberman 1 the soft blocks, exit tile and power-up locations are altered based on what frame you start the game on. They should be predictable the whole game. Most people run Japanese since the early speedrun guides plotted the paths using it. Both PAL and North American releases have a 10 second or so delay from starting the game compared to Japanese. Doesn't count for the run timing but you'd have to roll your own routing.