Is there a non-stupid way to play notationist?

I figured I could type in the notes on my computer keyboard - which apparently you can but it doesn't let you type 'c' to register the note c. Ok, fine. Makes sense, it's arbitrarily setup to mirror a piano, fair enough. I hate computer/piano key mirrors cause the muscle memory is all wrong but it's a solid idea, maybe I can play with my MIDI keyboard!

You can use the an external MIDI device - awesome. Except, hilariously, there's no way to play flats. If I play an Eb on my MIDI keyboard, it's not counted - because it's ABOVE the E key, not below it, so obviously it's a D# now.

I would love to play this game but translating the note I recognize to a screen click slows me down a ton and is not a useful skill to build - that's not what I come here for.

Has anyone found a way around this?