This archive represents important preservation of KS community history, so thank you for keeping it updated. (Thank you especially for including my own assets as well!)
After downloading the latest version of this archive just now, I decided to have a quick browse through my own personal collection of KS community assets to see if I could find anything that your archive is currently missing. This quick search resulted in me uploading about 45 files to the Dropbox upload link that you provided. Whilst I'm sure I made some mistakes in my haste (skipping needed files, uploading un-needed files, uploading assets that might be "banned" from use) I otherwise hope I was able to provide a mostly-helpful contribution to this project.
Let me know via private message whether there's anything else you can think that I possibly could do to help.
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EDIT: I found a couple of extra gradients that I had missed and uploaded those to the Dropbox link. I might have also uploaded the custom music I made for one of my old custom levels, but I've already forgotten.
There's something else I found where I felt I should ask first before I uploaded it: somewhere in my PC I've found a folder full of assets from Nifflas' game "Knytt" which have been converted into Knytt Stories assets by a user named Looki. This package includes conversions of all of Knytt's music, ambiences, gradients and tilesets as well as Custom Object representations of some of its animated elements. Is this the sort of content you would want to have in the archive? Or would it not be appropriate?