For the person asking about the latest updates - the "tagaya" server still responds to requests. It returns a list of every single existing update title and its latest version, and doesn't require dauth. It isn't the most useful thing in the world, since you can't actually download the updates (requests to the "atum" server for geting cnmt IDs and downloading NCAs doesn't work anymore), but you can get the latest versions. I don't think CDNSP uses tagaya - it uses the "superfly" server to get the latest update for each individual title, which is no longer accessible. The CDN downloader I wrote does use tagaya, which is how I know it still works and I have all of the latest versions... I just can't download the actual update files.
This is not for the layman, but the tagaya server is at
https://tagaya.hac.lp1.eshop.nintendo.net/tagaya/hac_versionlist. It is accessible just by going to that url with the most recent public cert (up to you to figure out how to send the cert to that URL, or copy some CDNSP python code into a new file and use it to make a request to that URL).