tried to set up one of my own. First of all, the guide is misleading, in that that the note ranges aren't c3-c5, they're c2-4 according to the example midi file that is downloadable.
Second of all, the timing issue never goes away. The log keeps telling me that the notes are too close to one another.
First I checked every single note by hand.
didn't work
Then I made all the intervals 50ms longer, just in case.
didn't work
I used an entirely different Midi track with only 2 notes that were spaced one minute apart.
didn't work

What am i supposed to do? The guide is lackluster at best and there's bound to be no community around this game if creating a file is this difficult.

Also as someone's already mentioned, the "timeOfFirstNoteInMainVoice" being in miliseconds when the rest is in seconds... Just annoying how it isn't mentioned anywhere.

For "timeOfFirstNoteInMainVoice" in the json, those units are in milliseconds while the "duration" is in seconds. I had that wrong, and it kept telling me my notes were too close together.

I've attempted to make one, but I'm still getting errors?

"Note E4 has not enough time when ending at 0.6280333 and next note starting at 0.6292378"

There is no note during that section on that specific midi file..