Re: How many misroutings went through the USA or UK?
Traceroute would sorta work for fat-finger issues. So tracing to one of the IP addresses that was wrongly advertised might show it resolving some unexpected hops along the way to it's new blackhole. Because traffic ends up routed to something that can't respond.
Unless of course you're paranoid, in which case traffic was briefly directed to faked websites, and evilness occurred. Because Russia, obviously. It's much like the good'ol Internet hijack when Florida stole EVERYTHING!. Possibly due to some previously unknown NSA site there. Ah, AS7007, I still remember you..
Or it was just another in a long list of routing errors that propogated due to BGP making that easy. As for sources of Internet mysteries, try Team Cymru (who aren't in Wales), CAIDA, or even NANOG-