Toolchain editor needs UX work!
This isn't an issue so much as a milestone/meta-issue.
Due to time constraints I wasn't able to do as much with the toolchain editor as I wanted.
The functionality is there, and stuff basically works, but 1) it's pretty ugly 2) the UX isn't so great.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information