You didn't ask how Italy felt. Apparently though, a common Polish-Hungarian border was something he favored, even while the Germans opposed it very much.
UK - hmm, they have more in the way of excuses to avoid making any commitments on Central European borders.
France- in terms of pure strategy, they are going to be inclined to think of Poland and Hungary more as Allies, but British standoffishness gives them an excuse for inaction.
Romania- allies with Germany against Hungary, while seeking to avoid direct fighting with Poland, in which they have no interest.
Soviet Union? No more likely than OTL to be offered a credible alliance by the west, likely to side with Germany to revise the Polish border.
On the other hand, if for some reason the Soviets prioritize their claim to Bessarabia and focus their hostility on the Romanians, they may go for Bessarabia, and thereby be indirect, de facto allies of Poland and Hungary, and may seek Bulgarian support to make despoiling Romania easier by doing it from all sides.