HighCharts has a global object lang that affects all the charts on a screen. It is a property of HighCharts and not of each chart instance. Therefore when used, it needs to be defined before the component itself.

Until OutSystems Charts v1.1.5, it was not possible to change the lang object at the application level. 

To give more flexibility and allow customization, OutSystems created a window variable window.OutSystemsChartsWeb. By default, it will take the Site Property values that you can manipulate on your screens.

How to use it? 

Add the following script to the top of the screen: 

<script>
	window.OutSystemsChartsWeb = {};
	window.OutSystemsChartsWeb.thousandsSep = '<your symbol>';
	window.OutSystemsChartsWeb.decimalPoint = '<your symbol>';
</script>

Note: The script must be placed on an expression before all Charts instances in order to be executed before the Charts get created.