How to add a custom action button to the "Counterparty Address" detail for mobile edit page in Freedom UI

You need to create a custom detail generator(look at the example in Terrasoft.FileAndLinksEmbeddedDetailGenerator)

After that, create schema and add to manifest:

Ext.define("Terrasoft.configuration.CustomEmbeddedDetailGenerator", {
    extend: "Terrasoft.EmbeddedDetailGenerator",

    generateItem: function() {
        var config = this.callParent(arguments);

        var cardGenerator = this.getCardGenerator();

        var isEdit = cardGenerator.isEdit();
        if (isEdit) {
            config.xtype = "my_embeddeddetailitem";
        }
        return config;
    }

});

Create detail component with button 

Ext.define("Terrasoft.configuration.MyEditEmbeddedDetailItem", {
  extend: "Terrasoft.controls.EditEmbeddedDetailItem",
  xtype: "my_embeddeddetailitem",
  initialize: function () {
    this.myButton = Ext.create("Ext.Button", {
        text: ""
    });
    this.myButton.on("tap", this.onMyButtonTap, this);
    this.element.appendChild(this.myButton.element);
   this.callParent(arguments);
  },
  onMyButtonTap: function() {
    Terrasoft.Geolocation.getCurrentCoordinates({
        success: function(latitude, longitude, locationObj) {
        
        },
        scope: this
    });
  }
}

In RecordPageSettings metadata set generator xclass for detail
{
    "operation": "insert",
    "name": "AccountAddressDetail",
    "values": {
        "generator": {
            "xclass": "Terrasoft.configuration.CustomEmbeddedDetailGenerator"
        },
        
    },
    "parentName": "settings",
    "propertyName": "columnSets",
    "index": 3
}