[SalesForce] Custom Label does not work on Lightning Components

For custom objects that are part of a Managed Package this is done slightly different, because you have to override the values provided in the package:

1. Click Setup->Translation Workbench->Override
2. In the override screen, select the Managed Package that contains the field you want to relabel
3. Pick the Component that you want to relabel (in this case, Custom Field)
4. Pick the object that contains the field
5. Pick "Field Label" (or whichever aspect you want to override)
6. The rest is same as 'normal' fields

The reason that you only have to do this for 'English' is that the Managed Package's language is probably English and thus they have provided only the labels for that 1 language. So only 1 set of labels to override.

My current workaround for this is to add a server side action (custom labels work in apex) that would return a map of all the custom labels used in the component and then set it as an attribute of type "Map". (You need to reference all custom labels anyway in order to include them in a managed package)

bottleneck: You have to make sure you load labels before doing anything else. If you have nested structure of your components and you load labels only once in the root component -> you have to manage loading of custom labels to insure the labels attribute is accessed only when it's populated.

Apex controller:

@AuraEnabled
public static Map<String,String> getCustomLabelMap(){
    Map<String,String> customLabelMap = new Map<String, String>();
    customLabelMap.put('MyCustomLabel1',Label.MyCustomLabel1);
    customLabelMap.put('MyCustomLabel2',Label.MyCustomLabel2);
    return customLabelMap;
}

Lightning Component:

<aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
<aura:attribute name="LABEL" type="Map" access="private"/>

<lightning:button label="{!v.LABEL.MyCustomLabel1}" onclick="{!c.myFunction}" />

Lightning Component Controller:

({
    doInit: function (component, event, helper) {
        var action = component.get("c.getCustomLabelMap");
        action.setCallback(this, function (response) {
                var LABEL = response.getReturnValue();
                component.set("v.LABEL",LABEL);
        });
        $A.enqueueAction(action);
    },
    myFunction: function () {
        //myFunction
    }
})