difficulty with MIDI export 4.2.1.2nnnn

I started with a simple composition I had made on a keyboard (Korg Titan Extreme) then exported to MIDI to visualize, clean and enhance the piece in muse. as a learning project. Getting it BACK onto the keyboard as a new performance was VERY challenging.
The biggest hurdle to start was there are only two MIDI channels 1,2. This means it works ok if all I'm doing is exporting a dual piano staff. While this is OK if the purpose of the export is to print the staff, exporting to a keyboard means two midi channels are being used to perform something only requiring one midi channel to reproduce. I had to merge two staffs together to make a normal keyboard midi channel export. It was not easy as I could not find a feature to do that. Copy/paste always replaces and the other explode/implode tools changed the notes.

For the 16 instruments each dedicated to to a midi channel the export midi pretty much did the job requiring me to rename each export to an 8 char filename including the midi channel so I would know where to put the midi file in the keyboard composition. This was hours and hours of work which had to be redone each time I made an alteration to the score based on how the machine played the parts.

It would be very helpful if there was a "score" type of export which preserved the midi channels beyond channels 1+2.
The score midi didn't appear to do that and I have empty staves in the score for future work which get removed from the score midi.

Next problem is the plethora of MIDI CC (C:2 nnn) controls on every measure which I assume are part of the RPN control data used to reproduce some of the fine points of the performance. There can be from 4-40 or more of these per measure. While referring to controls here are C:7 commands at the start of every MIDI file which sets the volume of the performance. I've noticed every single one sets to 100. This cases every instrument to be set to Volume 100 (which I guess so some insurance to make sure every track is heard) but these have no relationship to the volumes set in the score mixer which would be more helpful. Another point in these settings is I have to edit every channel I import midi where I want to keyboard mixer to initialize the volume at the start of the performance. If I don't do that every instrument snaps the mixer slider to 100 regardless of where I had it even while overdubbing the slider mix only.

Last issue to cover here is hanging notes on the machine I import midi to. I struggled with this for a week trying to figure out what's going on. I have multiple voices on some staves (two cello for instance) using the score and note stems to divide up the voices as might be expected. These "mostly" play fine except when there are whole notes or ties in combo with shorter notes. The whole notes often hang and don't shut off even when that same voice has a new note on the next measure. I tried various ways to solve this using notation just for the keyboard performance to resolve this with no certain success.

Unable to see note ends in the Korg's event editor I finally decided to export to midi and back into muse to see if I could identify something and the result was quite shocking as follows.

scorenotes.jpg is a section of the score as written and displayed originally in Muse.

scorenotesmidi.jpg is the isolated instrument staff exported for the purpose of importing to the korg which results in the hanging notes as displayed when I re-import back into Muse. This is the Musie output untouched by any other program or device.

scorenotesscoremidi.jpg is the SCORE export to midi and re-imported back into Muse same as the file above.

Note all three look a lot different from each other and none of the midi exports/imports look like the original score.

Final comment. I can laboriously work around some of the effort to get the score into my keyboard but the hanging notes seem to have no solution and occur in a few places on two instruments on a 110 measure piece.
-Pv-