"Just checked. "συναλιζ%" (% is a wild card) is nowhere in the Septuagint nor New Testament, except Acts 1:4."
I thought that might be the case. This is a good reason to be hesitant to ascribe any broad allegorical meaning to the word.
Liddell-Scott, however, cites another source beside Acts 1:4, "Man.5.339", but I don't know what is it a reference to. It has
a separate entry for "bring together, collect, assemble".