Maybe I can help? When I was an undergraduate I did an independent study and wrote a term paper on this topic. I believe I covered the historical scholarship on Metternich's diplomacy, though there might be IR/Poli Sci stuff I am unaware of. I can consult my bibliographic material from that, but I'd like to get a better sense of what you've found already and what seemed deficient to you about it?

One note I would make is that the Concert is much more of a post-hoc construction of historians (with the problems that entails) than a system of diplomatic practice. Even in 1822, at the Congress of Verona, there's discord between the former allies.

I'm sure you've encountered Kissinger's writing, but besides that I will recommend a biography by Desmond Seward