8 Nov 2021, 21:47

@pjexposito

Are there any way to replace opensource Pico-8 core with the original program?

No.
Unless you are a developer who can rebuild the entire system yourself.

What file do I need to modify?

It is necessary to recompile the entire system.
And, it's against Recalbox's usage policy to use non-opensource emulators, so you won't get help for that here.