RealTracks do not follow MIDI notation because they are made from Audio recordings. You can replace a MIDI track with a RealTrack by using the RealTracks Picker window, but this will not follow what was previously written for the MIDI track.

In the new 2022 version, there is a new Playable RealTracks feature. This allows you to enter notes on a RealTrack using the MDII Hi-Q instruments, which sound better than regular MIDI. More info on the Playable RealTracks can be found in this video at 9:00: https://youtu.be/BS0yuTwhcCc?t=540

If you plan to write the music for the whole track though, it is best to use a MIDI SuperTrack.

Best,
Chantelle