With the amcharts4 I do something like this for the change tooltip and label text for the x axis with the CategoryAxis...

// change tooltip
this.xAxis.adapter.add("getTooltipText", (text, target) => {
    const value = text ? parseInt(text) : -1;
    return this.getAxisToolTipText(value);
});

// change label
this.xAxis.renderer.labels.template.adapter.add("text", (text, target) => {
    const value = target.dataItem && target.dataItem.category ? parseInt(target.dataItem.category) : -1;
    return this.getAxisText(value, text);
});

But now, how to do the same for the Amcharts5 with DateAxis?

I will appreciate any suggestions.