So I've got to work with this set of code here for a re-write, and it's written by people who speak both English and French.

Here's a snapshot of what I'm talking about (only, about 4000 lines of this)

function refreshDest(FormEnCours,dest,hotel,duration) {
    var GateEnCours;
    GateEnCours = FormEnCours.gateway_dep.options[FormEnCours.gateway_dep.selectedIndex].value;
    if (GateEnCours == "") {  
        FormEnCours.dest_dep.length = 0  
    } else if (FormEnCours.dest_dep != null && FormEnCours.dest_dep.type && FormEnCours.dest_dep.value != "ALL") {
      if (Destinations[GateEnCours] == null || Destinations[GateEnCours].length == 0) { 
          RetreiveDestinations(FormEnCours,GateEnCours,dest,hotel,duration);
      } else { refreshDestSuite(FormEnCours,GateEnCours,dest,hotel,duration); }
    }
}

function refreshDuration(FormEnCours,GateEnCours,DestEnCours,hotel,duration) {
    // Refresh durations
    var FlagMoinsDe5Jours = "";
    var Flag5a10jours = "";
    var Flag11a16jours = "";
    var FlagPlusDe16Jours = "";
....... 

Is there any approach that I, as a speaker of only one of these languages, can use to make this entire process a lot less painful for both figuring out what everything does, and then refactoring it?