Not sure what's wrong with the first code block, but for the name not showing up...
messageClient(%obj.client, '', '\c6You caught\c3', %col.client);
needs to be
messageClient(%obj.client, '', '\c6You caught\c3%1', %col.client.getPlayerName());
%mini.messageAll('',"\c3" @ clientTeamName(%obj.client) @ "\c6 captured\c3 " @ clientTeamName(%col.client) @ "\c6!");
also needs to be
%mini.messageAll('',"\c3" @ %obj.client.getPlayerName() @ "\c6 captured\c3 " @ %col.client.getPlayerName() @ "\c6!");
and for more network efficiency:
%mini.messageAll('','\c3%1\c6 captured\c3%2\c6!',%obj.client.getPlayerName(),%col.client.getPlayerName());