Territorial extent and Political Ramifications of a Surviving Austria-Hungary from a Successful Sixtus Affair

In a desperate attempt to end the chaos of the war, Kaiser Karl I of Ausria Hungary tried to broker a separate peace agreement with the Entente through his brother-in-law Prince Sixtus of Bourbon-Parma. In otl the negotiations largely fell through because of the Austrian Foreign Minister Czernin's aggressive speech which angered Clemenceau to leak the negotiations to the public. But supposing these negotiations were successful, what would the borders of a surviving Empire look like. How would the other Central Powers react to Austria signing a separate peace deal? What would Europe look like in the aftermath of the War? What sort of political developments would take place within the Empire? How would Austria-Hungary affect WW2 moving forward? Would a precondition for this settlement be a more decisive Caporetto offensive such that the KuK army looks poised to occupy Venetia?

Could Italy go Communist here or perhaps have an earlier Fascist type dictatorship? What would Poland look like? Could it possibly end up as a monarchy and ally with Austria-Hungary to support the Russian Whites or perhaps against a Revanchist Soviet Union? What would the Balkans look like? Instead of Yugoslavia would the Serbians just take Bosnia as part of a Greater Serbian Kingdom?
The problem with the entire affair is that Karl was very generous with things belonging to other and one of the entente precondition was to at least adress the italian claim aka giving up some territory, thing that the A-H totally refused.
By the time of Caporetto with Russia out there were no incentive for the separate peace even because Germany had a much greater control over A-H and frankly in case of separate peace we can probably see Germany try to do occupy A-H like the Nazi have done to Italy in 1943.

In the scenario where the proposal is accepted, the Anglo-French basically throw away in total ltaly, as not only A-H refused any territorial compensation towards Italy but even want Albania as part of an enlarged Serbia...naturally under an Hapsburg monarchy and basically a puppet.
Russia will be left alone and get the B-L treatment and Romania will go OTL, while Bulgaria will be immediately try to sign a peace with the Entente .

In the mind of Karl the border of the Empire will be the same of pre-war except:
- some loss in Silesia to compensate Germany over A-L
- border adjustment in Romania
- transfer of Erzegovina to the puppet Serbia, probably with Montenegro and Albania.

Italy if left alone will be forced to accept this but this will mean a lot of diplomatic repercussion, probably defaulting their debt towards the British and decades of hostility towards them. Hardly a communist regime is possible even because in this scenario the October revolution will be probably butterflyed away but an authoritarian regime with some democratic veneer will be the most probable outcome
Maybe the rest of the entente will try to soothe Italy with colonial and financial compensation but for the first they also want a lot of them and are not in the sharing mood and at most can go the OTL and give up some useless scrap and for the second is not that their financial situation is good enough to be very generous..

The big problem in this scenario is that kind of separate peace give advantage only to A-H, sure it free some Entente resources but also a lot of German resources in A-H, it also mean that if they ask Italy like OTL to send troops in France as help, the answer will be a very detailed explanation of what kind of job the Queen and all the females of the goverment members of France and UK perform