EDIT1: It looks that quicklaunchbarX.desktop entries I try to create appear as normal desktop entries in launcher. Currently I have 2 (functioning!) "Phone" icons in launcher. Obviously one is from /usr/share/applications/call-history.desktop entry and the other is from ./local/share/applications/quicklaunchbar0.desktop entry. So quicklaunchbarX.desktop edited entries are not recognised as such. We have to find a way to make them so. .
ln -s /usr/share/applications/mail.desktop /home/user/.local/share/applications/quicklaunchbar3.desktop