Unless they completely fucked off from their African and South Asian trade partners, they should be relatively fine.
Also, why have they not switched to a social corporatist tripartite economy? Yeah, Keynesian economics were doomed to stagnate, but austerity and socialism are not the only ways out.
False equivalency. One is a state-controlled dictatorship, the other is a militarist liberal democracy with economics that should actually work.
Let me highlight those words and make a response. Again, this reflects the bias of TL that developed over time.
One thing is that I remain resolute to the words "Socialism or Barbarism". Keynesianism is doomed to stagnate and there is no way out but socialism.
It also actually contradicts your statement about "economics that should actually work" because what you see that should actually work, the FBU already has it and has worked... but not for much longer. Even earlier versions of the TL mentioned that the FBU is doomed to fall anyway so what's the difference. I also don't see any difference between a "corporatist" economy that you advocate and Keynesian economics given that the FBU is very much a social corporatist tripartite economy itself since the wartime era reforms. Keynesian theory supports the establishment of this economy and yes, at some future time, the FBU has to give up something between supporting a comprehensive welfare state, provide profits for capitalist firms and then spend a lot on armaments because those three will not forever support each other. The US with a bigger economy can't do it IOTL. What makes the FBU special that it can do it with less favorable circumstances? It's not just about economic systems or actually it's less so about "economics that should actually work". It's about geopolitical circumstances and resources. ITTL, the FBU do not have it. The Comintern has it. IOTL, the Soviet Union do not have it. The capitalist West has it. At some point, the FBU has to go something "neoliberal" and with the circumstances of TTL, that neoliberalism has to be backed up with more appearance of exercise of police powers and force, thus "more junta-like". IOTL, we can afford it even though Reagan and Clinton did a lot of stuff that substantially is very illiberal but ITTL, capitalism can't afford it. It's a lot less than that of Pinochet's Chile, of course, but as mentioned, the FBU is more Singapore, Japan and South Korea... than Germany or Scandinavia of OTL.
And regarding "f**k*ng off their partners in Africa and South Asia? The FBU may look liberal democratic appearance-wise but it's still an imperialist state and I don't see Africa and South Asia not being f**ked up by the metropole... It's just the way it is. Of course, the FBU can't afford to keep the colonies as source of raw materials and that's it but the FBU will make sure that the economic framework with the Commonwealth is deliberately to its favor, not as something fair. For all of the growth of India ITTL, India will remain servile to Britain that's for sure.