I just noticed...all my other plugins are named cheat.plg, yet the Gen one is MH_Generation.plg and the one from that link is speedfly.plg.
Do I rename it back to cheat?
I've placed the plugin in the folder.
Then I use the ntrswitcher and use 3.4.
The game actually boots this time but it crashes when trying to load the save.
Maybe I could try renaming one of the new files to ntr.bin and try with the old app?