Bad and good news:
Good. Since MK2 was released quite some time ago, it is more or less known how it communicates.
Bad. No one has done anything for Sonar/CbB support for it.
What can you do depends on your programming skills and/or willing to invest time or money:
1) if your are somehow experienced in programming, using the information from f.e.
https://github.com/git-moss/DrivenByMoss you can check the communication yourself. You will just need to understand what/where to send using any OSC client. Then check it works using AZController OSC or not. If yes, you will get transport working. If not, I will need to adjust the code so it works.
2) if your can not do (1) yourself, but is ready to invest some time. We will need to organize online session, with TeamViewer+Skype installed on your DAW computer (where MK2 is connected and NI driver installed). So I can do (1) remotely
3) if your do not have time, but have money. You can buy another controller for me, so I can do (1) locally.
While (3) may sound crazy at first, think about reversed approach: should I, not working for NI nor BandLab, spend not only my time but also my money to make transport buttons working on your controller?
Note that it is unlikely you/we can achieve much more then just transport within short time.