Evap coolers will be even worse as I presume they increase humidity, 35c low humidity is FAR more tolerable than 25C high humidity. Also if a baby has a fan wafting over it all night I would be very worried about dehydration.
Listed building meaning the windows don't open? Eh, rented? I'm fairly sure that while listed means big changes externally are a major fight with the powers that be, making the houses unlivable isn't the idea, if you own it, make the windows open. If that means replacing windows with ones that look the same externally but can be opened, thats what you need to do, if you rent, I would assume you could make a complaint about it to someone that would force the landlord to provide windows that open. Not least, surely that is a fire safety issue if there is only one potential exit. Doesn't any bedroom need a window that can open in a way to allow escape legally?
Anyway as for good portable AC units... basically no, I would assume many are significantly better than they were when I got this, but many are just as bad, stupidly loud, effective but very loud. A split unit where the compressor is both outside, the main extraction fan doesn't need to shove a lot of air down a small tube and it can be firmly and securely attached all mean split units are more efficient, cheaper to run, massively quieter and seeing as most people have loads of wall space and not a lot of floor space, it saves a buttload of space and issues.
You can get ones with a removable liquid collector, I had one of those first time, worked fine but would need frequent removal in really humid weather, that one died and the next one worked to evapourate the condensation water into the hot exhaust so needs no emptying. Both work fine and make a MASSIVE difference to temp of room and comfort/humidity of room, but so loud it can almost drive you mad.