Wanted to start getting into running Nosferatu: Wrath of Malachi but I hate 4:3. I found a mod online, not going to post links just in case, that allows changing the aspect ratio to 16:9/10 but it involves uses a new modified exe version of the game. I was wondering if this would be allowed for speedrunning or if I should just go back to the old 4:3 exe.

I don't believe the mod changes anything else except the aspect ratio/resolution but I could be wrong. My apologies if this is the wrong area to ask this question, relatively new to the site.

You need to contact the mods of the game, they’re the ones that make those decisions and rules.

Thanks so much for the quick reply. Will do.

Generally speaking, mods are almost never allowed in speedrunning (and, IMO, "I don't like 4:3" isn't a great reason to allow one). But yeah, as @Timmiluvs said talk to the moderators.