I have some vague ideas in my journal, if it's any help/use! But god, yeah, Londo's arc is so heartbreakingly good. I can't believe a war criminal is one of my favorite characters, but I guess one of the funniest things about B5 is that at least half the cast has personally done a war crime, even the ones you initially assume are 'good' (not that morality is EVER black & white on this show hahahaha), but also are personally called to account for them at some point in the series.
I think his arc is fantastic & I would make no changes but also I love him and would like something better to happen to him haha. The Prophetess DID say he had three chances to change his fate!! Stop casually damning your people to oblivion by bitching about the old days in the hallway to some random creep, Londo.