Im wondering what's going with the Czechoslovak Legion in Russia, and how this current Army without a home is going to impinge on A-H. They are currently retreating back to Vladivostok, but i doubt that France or Britain is particularly inclined to finance their journey to either country, the US could, being represented as freedom fighters and part american volunteers, I do not see anybody else wanting them. It would be real cool if Karl could figure out some amnesty for allegiance, use them to help suppress pro German rebels/rioters, polish separatists in the Zaolzie areas, etc. I really doubt this is at all plausible but it would be cool.
If Karl does that, he will have lost his credibility for good and Austria-Hungary will collapse.
The outcry in the German population, Germany itself and Hungary would be immense.
It is simply not acceptable to pardon traitors who wanted to destroy your empire and then use them to suppress a political opinion.
Hungary would immediately break away from the empire, the German parts afterwards and start a civil war to get rid of him.
It would probably end with Charles being publicly executed and his family exiled to England or something.
The Germans would certainly not help him. I'm not even sure they would intervene at all to keep Austria Hungary.
From the German point of view, they are to blame for this war, could not even carry their own weight and would need constant help and when Charles came to power he tried to start secret negotiations to break out of the war and leave Germany alone in there.
The country that saved them several times.
Now when he starts pardoning traitors and suppressing the German Austrian population and others it is enough for the OHL and the German government. And let's not think about what the German press and population will say.
So, what I want to say with this long explanation is that the vote will not happen because Karl will definitely initiate the end of the Habsburg dynasty and of Austria and Hungary as a state.