The shorther the war is for France (and everybody else), the better. For starters, France will be better off if the Hundred Days do not happen (France keeps some Revolutionary conquests it lost in 1815), and the population will be bigger as a shorter war means less casualties. Or at least that's the thing on paper. IOTL the French lost close to a million and a half men during the entire cycle of wars put together, a higher percentage of their population than during WW1, mind you, which was of roughly 1.3M, extrapolating the losses to France's 1914 population would result in 2.1 million casualties. So yeah, France's demographics will improve compared to IOTL with a shorter war. Most of the battles of the Napoleonic wars took place outside of French soil, meaning France escaped most of the war destruction suffered by Spain or Germany, plus the Coalition was very lenient with payments IOTL of 28 million pounds and a debt that did not even reach 200 million pounds until 1830 (compared to Britain's 848 million in 1815). So yeah, you can safely assume that ITTL France will be stronger than in our own timeline.So it's time we see Bonaparte finally fall... Although he may lose, I got a feeling France will at least have a better hand then IOTL.
Spain tried IOTL and resulted in a whirlpool of violence and coup attempts as Ferdinand refused to concede any power and had the support of a population willing to see the king return, plus he avoided the Spanish army all the way to Valencia where in the Manifest of the Persians denounced the Junta and assumed full control. As a little spoiler, that's not going to happen here. This does not say that things will be pretty, though.Spain seems to be doing better, at least I hope that when the war ends, Spain at least begins to restrict the power of the king.