When you start kickshaw on terminal what does it do? Mine works fine.
What does your ~/.kickshawrc looks like?

% more .kickshawrc
# Generated by Kickshaw GTK3 1.0.43

[VIEW]

sf-showmenuidcol=true
sf-showexecutecol=true
sf-showicons=true
sf-setoffsep=true
sf-showtreelines=true
sf-elmviscol=false
sf-highlightingstate=true
sf-gridstate=no_grid_lines

[OPTIONS]

sf-createbackup=true
sf-usetabs=true
sf-separaterootmenu=true
sf-sortoptions=false
sf-notifyaboutconversions=true
sf-useheaderbar=false
sf-showmenubutton=true

% mv ~/.kickshawrc ~/.kickshawrc.tmp
then copy the above contents into a new ~/.kickshawrc
and try it.

If not maybe gtk3 is messed up, have you substituted gtk3 with one from AUR?
% sudo pacman -Rdd gtk3
% sudo pacman -S gtk3

I don't remember editing it, I don't why it would be different :)
I use openbox, and I think all kickshaw does is use .config/openbox/menu.xml. so it just helps making a fancy menu.
I just tried it a few times, I think jwm uses it in my last setup, but I generally use obmenu-generator.

I wonder why the default install put a configuration file that make crash the software

Because i do not install and use openbox every day :).
So if nobody make a report like you did, i don't see the trouble. Thanks for your help.