How is the Art Gallery fight impossible?
Physically impossible, in that Bond (and likely Mitchel too) would end up with a dislocated pelvis, broken neck, numerous and possibly lethal cuts from the shards of glass, broken ribcage etc.... That and the level of acrobatic expertise required without any kind of safety support for two nearly 40 year old operatives. Even as athletic as Craig's Bond.
I rather think the Thunderball briefings, though sumptuous, are very... well, Anglo-philic; they reflect the view of "back then" that the English commanded a noble empire they could track nuclear weapons across, not the second-raters who're scrambling to get a lead over the CIA, as depicted in QOS).
Which is why Thunderball sensibility and Young's is light-years closer to Fleming than Forster's.
Either way, it's mostly down to the script, and various re-writes.
As for YOLT, the film, I feel those briefings in the "American war room" are rather stuffy and inconceivable; as well, the geodesic domes in the Artic, as meeting places, is absolutely ludicrous... as is the entire concept of "stealing spaceships", so obviously cribbed and expanded from the similarly Space-Aged concept of "toppling" in Dr. No.
... Again. You're talking about Roal Dahl's script, not Gilbert's direction. IIRC, those geodesic domes were shot in Whitby, North Yorkshire, possibly doubling for Canada. Not sure where you got the Arctic from.
Compared to QOS, YOLT the movie's entire plot seems like something out of Flash Gordon, and DAF is merely a farsical re-rendering of it.
Plot-wise, I give you that. However, in terms of tone and mood, I'd argue Diamonds Are Forever is a great deal closer to Fleming than QoS.