The thought of your interest in a surviving Bourbon Restoration both makes me smile (that someone considers doing so), and nervous (that if it would be even possible with Charles X still on the throne, personally I don't see him as pragmatic, or if he is, less so than his brother, Louis XVIII)
That being said however, long-term, is Louis XIX still does so, it's certainly plausible for the constitutional monarchy issue.
Spain still has to deal with the Carlist Wars if Ferdinand VII does not sire a male heir, and even if they don't, the Liberal faction isn't going to go away anytime soon.
The Two Sicilies, it's implied that Francis I had liberal ideas, but ultimately charted a conservative course upon acceding in 1825, so it's a matter of somehow convincing him to continue with the liberal ideas, even if it's not overly so (then again, that comes from Wikipedia so take that with a grain of salt).
Piedmont will be tricky, as it is ruled by Charles Felix, who is a true and true reactionary, convinced that all of the trends started in the French Revolution would be swept away and that the order prior to 1789, that is the style of absolutism without enlightenment, would be the law of the land now and forever. He dies in 1831 though, so make of that what you will...
Belgium...I see that as very unlikely, not unless it wants to risk war with the British, the Dutch (since it is the Southern Netherlands after all), and probably the Prussians.
Personally, long term effects of a surviving Bourbon Restoration, even if Louis XIX follows up on his constitutionalist policies, I can see some liberalization, but whether or not it'll placate the French Liberals is up to debate. And then here's also Algeria...