It IS possible to do all these things and more.
It might not have been likely that Labour under Corbyn managed to do them.
But these are things that can be done, with the right forces at play.
What exactly do you mean by 'international commitments'?
Since yr asking..... a few things that would've been under threat from a Corbyn premiership (sourced from here: https://capx.co/on-salisbury-and-syria-the-labour-leadership-got-off-lightly/)
Funding for the White Helmets in Syria
UK Training for Ukrainian troops
EU sanctions on the Nicaraguan dictatorship
The situations you cite are obscenities but the idea that a man of Corbyn's vast incapacities would be able to impact on them is I think, bollocks. I suspect that we would've simply see a foreign policy switch to backing the positions of other global and regional powers like Russia and Iran. This is what has happening with LOTO's policy on Syria after all, where they get very exercised about entirely symbolic bombings of empty airbases while remaining absolutely silent on Russia bombing hospitals. This got to the point where it was apparently a resigning matter for one of Corbyn's top team. See also the recent STW protests about the assassination of Soleimani which managed to frame it as entirely about US aggression while neglecting to mention his many, many crimes. This is ultimately what fucks me off about him - the foreign policy is based on campism not the consistent application of principles of Human Rights.
Incidentally, The Sunday Times has an exclusive today that as part of Corbyn trying to cement his legacy, he's (possibily) planning a trip to Iraq! I'm just going to nick Oz Katerji's tweet as he's said it pithily: "If he does go, it will be to tell the Americans who aren’t shooting civilians in the head to leave while ignoring the Iranian militias currently shooting civilians in the head".
So, just to clarify, in your opinion, the issues you mention (including financial and military support for an army that contains an active neo-nazi battalion) trumps any possibility of amending a foreign policy alignment that has directly and indirectly resulted in 10's of millions of deaths since WWII, has supported (and continues to support) multiple authoritarian and genocidal regimes, has deliberately eroded international law, foments and escalates conflict through the sales of arms and perpetuates the continued threat of nuclear conflict?
It hugely weakens any moral case that they (i.e. Corbyn, STW) might have. It looks like campism - picking one side over another - with wilful blindness 'cos that's what it is. To take a current example, I think to support democracy in the ME we should support the current wave of pro-democracy protests taking place in Iraq and Iran. But where's the Left's position on that? Do they even notice its happening? And the anti-war left will be even worse, balls deep in conspiracy thinking if they even notice - "US regime change" and all the usual shite. (Oz K on Corbyn's mooted visit to Baghdad: "They wouldn’t have a clue who he is and I’ve never met an Iraqi who has even mentioned Tony Blair’s name in passing conversation. The country is not stood in stasis looking backwards at 2003, that’s just the Corbynite left"). To take a different case, divesting from the arms trade, stopping selling arms to Saudi - how do you tackle that outside of Parliament? And how can that be done without a united party? MPs and members together, not as Corbyn has done, leveraging the latter against the former. I agree with you currently that it's off the agenda, out of sight, out of mind, business as usual and I don't think that's good or acceptable but I would have much more time for the STW positions on this stuff if they seemed to acting from moral principle rather than the aforementioned campism