So, I know this is really random, but I could've swore I downloaded all of South Arcade's songs onto my pc ages ago, and on reconvening after a vast while, now they're no longer there, just as they're not there in the search anymore? Is there a link between downloaded cdlc and your game file storage area? I feel like I'm going insane....

Also, does anyone have the p.psarc files for the South Arcade songs they can share? And at even a longer shot, the lead and rhythm for You Know My Name by Chris Cornell?

I check Ignition almost every day and don´t remember ever seeing a song from South Arcade on here.
There is a request section on site if you want to request songs

No worries, you aren't going insane. I used south arcade in week 602 of the championship and I downloaded a couple while they were still on the site. Click on the highlights for the links. The charter took them down the site thats why its no longer on ignition, so if you download them don't upload them to ignition unless you rework them.

the chris cornell song is actually still on the site under the username abandoned (if you can't find a song and it was on the site it might get put there, usually songs there could use some tweaking/ arent the best. which is why they set it to hide by default. You access abandoned by turning show abandoned in the filters section):
https://ignition4.customsforge.com/cdlc/23476

If either were on your pc and you don't think you deleted them i would highly suggest you download the app called everything (orange magnifying glass). Windows search is pretty awful meanwhile everything will find the files on your computer.

Hope this helps, and if you have spare time feel free to check out this weeks halloween songs in the championship (or any future ones posted every saturday):
https://customsforge.com/topic/81491-rocksmith-2014-championship-week-679-haunted-riffs-halloween-hits-monster-grooves-supernatural-shredding-%F0%9F%8E%83

both of you and anyone reading is more than welcome to join.