I have replaced this:
"{xen:phrase online_now_x_members_y_guests_z_robots_a, 'total={xen:number $onlineUsers.total}', 'members={xen:number $onlineUsers.members}', 'guests={xen:number $onlineUsers.guests}', 'robots={xen:number $onlineUsers.robots}'}"
With this:
{xen:phrase...