Alston Release - January 2015 - Pattern Tool
Alston Release - January 2015 - Midi Time Stretch
Alston Release - January 2015 - PRV Zoom
 

Oh, you mean "MIDI editor", not MIDI. The latter hasn't seen significant additions since 1999.
 
Wasn't the pattern tool introduced in SONAR 4 or 5? I don't remember, as I have never used it.
 
 

Pattern Tool is part of the Alston Release. It's that paint roller tool, where you can copy and roll out the pattern.

MIDI Stretch. Hold down the Shift/Ctrl keys and you can stretch or contract a midi clip.

Was that in Alston or before?
 

One of the most important features that CW released is a PRV zoom that is very useful. 

When was that added?

Kamikaze
When was that added?

Jan 2015. There have been a lot of MIDI enhancements in the last two years. If you look at the rolling updates page it will list most of them. Here is a vid of some of them.  https://www.cakewalk.com/.../SONAR/Rolling-Updates

Here's a few.
 
Pattern Tool
Onscreen Virtual Controller
PRV Enhancements
The new PRV features more realistic piano keys, optimized vertical zoom resolution, and many other improvements.
MIDI Enhancements - in many of the updates
SONAR now allows for MIDI time-stretching, velocity layering, and additional functionality to make editing MIDI even easier.
50 fixes and enhancements for the Piano Roll View in Cambridge, more in Dorchester and most updates sinceetc etc
Better Drum Maps

So again, two years ago, not really in the last two years, It's January 2017 now. Nothing has happened since Alston with any new MiDI editing functions.
 
I had missed the very bottom of the screen when I posted, my firefox has been loading funny this evening, but it's all two years ago.
 
Hopefully they add something before the end of this month, So I can't make a post i February listing nothing in the last two years.