can i use the nes nostalgia emulator? it uses almost 100% of the fcuex engine

i used it for my runs when i barely started out, there were no issues with verification

If you can, use the Mesen emulator, for it is the most accurate NES emulator because of its cycle-accuracy.

well i use smbgames.be so is that ok

Mesen is legal for SMB3, but not for SMB1. Mesen also does not have an autosplitter for it, only FCEUX. Makes issues sometimes.

is smbgames.be mesen