FusionTime Tooltip Custom / Edit Column Name

[NullPointerException]

I am evaluating FusionCharts and FusionTime. I am using the Json data option and my column names for the plot are like "cummulativeMarginPercentage". But this looks really bad in the tool tip. Is there anyway to edit this value or to use the actual Axis Title?

this.dataSource = {
          chart: {
            multicanvas: false,
          },
          data: fusionTable,
          caption: {
            text: 'Cummulative Margin Over Contract Life'
          },
          navigator: {
            enabled: false
          },
          xaxis: {
            binning: {
              month: [1],
              day: [],
              hour: [],
              minute: []
            }
          },
          yaxis: [
            {
              title: "CPC Costs",
              plot: [
                {
                  value: "costs",
                  type: "column",
                  aggregation: "Sum"
                }
              ]
            },
            {
              title: "Cummulative Margin %",
              min: 0,
              max: 100,
              round: true,
              plot: [
                {
                  title: "Cum",
                  value: "cummulativeMarginPercent",
                  connectnulldata: true,
                  type: "line",
                  style: {
                    plot: {
                      "stroke-dasharray": "0"
                    }
                  }
                }
              ],
              format: {
                suffix: "%"
              },
              referenceline: [
                {
                  label: "Margin Goal",
                  value: "65",
                  style: {
                    marker: {
                      "stroke-dasharray": [4, 3]
                    }
                  }
                }
              ]
            }
          ]

        }