[Solved]-Highcharts - How to show intermediate values on Area chart-Highcharts

You need to increase the density of points. Below you can find an example how you can do it programmatically:

chart: {
    type: 'area',
    events: {
        load: function() {
            var series = this.series,
                iterations = 2,
                i = 0,
                newData = [];

            for (; i < iterations; i++) {
                series.forEach(function(s) {
                    newData = [];

                    s.points.forEach(function(p, j) {
                        if (j) {
                            newData.push(
                                [
                                    s.points[j - 1].x +
                                    (p.x - s.points[j - 1].x) / 2,
                                    s.points[j - 1].y +
                                    (p.y - s.points[j - 1].y) / 2
                                ], 
                                [p.x, p.y]
                            );
                        } else {
                            newData.push([p.x, p.y]);
                        }
                    });

                    s.setData(newData, false);
                });
                this.redraw(false);
            }
        }
    }
},

Live demo: https://jsfiddle.net/BlackLabel/d8jq9bvh/

API Reference: https://api.highcharts.com/highcharts/chart.events.load