Good, that you are now looking into another direction,
doesn´t mean that Splat can´t be the reason for your probs,
but I´m editing here projects with 78 and more tracks ,4-8 synths aso  and
heavy duty fx per track-works  smooth as butter- you know?
good luck 

Another idea:
At what buffersize/bit depht  aso  are you running your audiocard?
 

And:
If I understand  right, you are running 2 audio interfaces at the same time,
the presonus for recording or so and a focusrite for playback..........?
I so, try using one !
regards

512 Samples I still have the same problem on different settings.

I have the Focusrite and an onboard soundcard which I am not using. The focusrite is running at 96k 24 bit depth with 512 samples.
 

Guys I think we are missing the point focusing just on this. StuntPickle, can you let us know more about the other 98 problems, maybe we can help there?

Stuntpickle
for some odd reason Sonar refuses to record expression

They don't include this feature.

I've seen this before but for me it was user error. By that I mean I was trying to edit controller data without the correct track selected.
Out of curiosity, how many tracks do you have open in PRV in your video?

A couple of things.

MIDI. Going on your first post your problems seem to be MIDI rather than audio related, so the audio interface doesn't seem particularly relevant.

The piano roll view screenshot. Are you certain it only contains data from a single MIDI track? If you're viewing more than one track at the same time then that might explain the brown MIDI CC events you can't edit and why you can write over them but they are still there. The new CCs you write being in a different track to the ones you want to alter.

Secondly issues with MIDI turning up in unanticipated or unintended places would seem to indicate a problem with MIDI routing somewhere. Possibly a hardware issue, possibly recording to more than one track without realising it. Possibly related to MIDI channels where data on different channels is being sent to different tracks other than the intended one.

If by "open tracks" you mean how many I'm viewing in the piano roll, then the answer is one. I still have the problem with no midi controllers connected.