MarsSeed [1] filed a deletion request for kamule [2]:

This might be considered for removal.

Development stopped 6 years ago.
Might not work with the current KDE5.
Also might not be really needed because it is just a 6 year old GUI
frontend
for Amule, which has its own GUI based on WxWidgets.

Also source is 404 because it is hosted on the problematic
linux-apps.com (the closed "OpenDesktop.org" platform),
which does not provide direct download links.

[1] https://aur.archlinux.org/account/MarsSeed/
[2] https://aur.archlinux.org/pkgbase/kamule/