If you want to try this, do so at your own peril.
If you have a copy of the Command.exe file that was associated with version 8.1, then do this: Rename the new version that you just got. So, you could make Command.exe into CommandA.exe. This way, you could go back to it. After it has been renamed, the program won't work until you provide a new Command.exe file. This is where your version 8.1 file comes in. Copy that file into the same directory (folder) and it will now be the new exe file for the game. If the program works as expected, then there was no problem switching it out. If it doesn't work, then delete the copy of the version 8 exe, and then rename your CommandA.exe into Command.exe. That will restore the new exe file and the game should work.
Do this at your own risk. I'm just a game player like you. I don't have any expertise with the file names of what is needed in this game. That being said, what I described is very simple to do.
Now, why do you want to do this? The new version seems to have fixed a bunch, and many of the errors that we have been talking about are relatively benign in nature. I believe that the program is close to being back to the CMANO standards, and CMO even has extra bells and whistles. So, what is it that you think is so screwed up that you want to go back to version 8?