What about Germany? I dont know anything of German politics in that era. I'm assuming a German favorable peace, that resembles victory would encorage militarism there. Were Germany by chance to suffer a embarassing or catastrophic naval defeat what would the consequences be? Were militaristic &/or imperialist impulses so strong in the population they would survive defeat? Or would the Kaiser be removed from guiding foreign policy & perhaps the naval policy discredited?
That would be towards the end of the Selbstherrschaft phase, so it would badly discredit Wilhelm and his admirals. How badly would depend on what happened. If the German fleet found itself in some tight spot due to logistical constraints and therefore lost, it could easily spun as perfidious Albion undermining Germany's rightful colonial ambitions by hogging all the good coaling ports. But an outright defeat might tip public opinion. The fleet was not universally popular, and the emperor already was a figure of ridicule to a significant part of the population. You might see a conservative shift towards Bismarckian policies, away from global playership.
A lkot of it would play out in the media. Wilhelm had a tin ear, so there is a good chance he'd offend people by insisting this was everybody else's fault. The question would now be whether the resources of the Flottenverein trump public revulsion. They will present the narrative "we lost because we didn't have a big enough navy" against the competing view "we lost because we can't afford to do this high-seas foolishness and need to concentrate on what we do well (i.e. beating the stuffing out of continental European powers)"
The chance of a revolution or palace coup is practically nil. But such a development is likely to embolden the anti-colonial, anti-naval faction and increasingly cut the emperor out of the decisionmaking loop. In the end, Reichstag and cabinet may end up fighting their way through several constitutional crises to produce a state run by the established elites in a semi-meritocratic fashion and with a modicum of democratic input while Wilhelm is slowly reduced to signing his papers and christening ships.