Puck MIDI Note On

Here's a link that reveals a bit more about the MIDI message format
NoteOnOff

value: [0x80, 0x80, 0xB0 + channel, controller, value],

If you change the 0xB0 to 0x90, it would send a NoteOn
If you change the 0xB0 to 0x80, it would send a NoteOff

If you configure a local projects in WebIDE and copy the module there, it will load that version of the module. Then you can try the changes. Look at the Gear-like Icon in the upper right of WebIDE. Select Project and define a location on your hard drive. Use you explorer to find that folder and a sub -folder called modules.
Add a new function to the module:

exports.noteOn = function(channel, controller, value) {
  NRF.updateServices({
    "03B80E5A-EDE8-4B33-A751-6CE34EC4C700": { // MIDI
      "7772E5DB-3868-4112-A1A9-F2669D106BF3": {
        value: [0x80, 0x80, 0x90 + channel, controller, value],
        notify: true
      }
    }
  });

Similar function for noteOff.
Worth a try.
The channel is the channel number, controller is the Midi note, and value is the velocity.