The file is xwbar.lst, and you have it.
But, as far as i understand
xwbar.lst contains the items that has been excluded from the wbar. Not those included - at least on this machine it works in that way.
Remains, that ~/.wbarconf contains only basic settings:
c: wbar --bpress --pos bottom --zoomf 2 --isize 32
but nothing about the apps included to it. Those values are in /usr/local/tce.icons wherefrom controlpanel > tcWbarConf also seems to read (and write) them.
So, one way to make changes permanent would be to include /usr/local/tce.icons into the backup list (?)
Or, when i delete the symbolic link to tce.icons (~/.wbar) and migrate the settings (by hand) to ~.wbarconf tcWbarConf, then, would read from that file?