So I was just wondering if runs are only valid if they are performed with the game versions listed in the guide by UM-4G, since all my saves and stats are on 2.9.1. Apart from a few bug fixes and graphics changes 2.9.1 doesn't seem to differ from 1.7.0 or 1.8.7. (Altough I could be wrong)

version 2.X.X is allowed

That's good to know, thanks!

All versions are valid, however I would recommend getting v1.11.1 from here: https://drive.google.com/file/d/1v1LKWKZ6eEuWwPlsvSJUCqDHaMo6b0N4/view?usp=drivesdk