How are you searching? I've switched my buildroot to use github.com for the feeds, as they were the worst offenders for 503s and 504s, and I'm wondering if you could do your work using the github logs...
(Or maybe use something like https://downloads.openwrt.org/snapshots/.overview.json - I have one of my daily tests diff that file as it shows all the new targets/subtargets/profiles.)