flat grid - get data property

Hi, I am trying to change background of one column data dynamically based on values from JSON (like BG color). 
I experimented with customizeCellFunction and closest I got is defining BG color field as ID and refer to it like this: 
function customizeCellFunction(cell, data) {
if (!(data.hierarchy && data.hierarchy.uniqueName == "koren")) return;
let newText =
`<p style='background-color:${data.recordId}'>${data.escapedLabel}</p>`;
if (data.type == "header" && data.member) {
let parts = cell.text.split(data.escapedLabel);
if (parts.length == 2) {
newText = parts[0] + newText + parts[1];
}
cell.text = newText;
} else if (data.type == "value" && (data.member || data.isDrillThrough)) {
cell.style['z-index'] = 1;
cell.text = newText;
}
}
 
And it works. 
 
Then I wanted to implement some URLs and aditional other BG fields but I got stuck since only 1 ID is supported.
I then saw option to use 'property' in JSON dataset but can't figure out how to refer to certain property in customizeCellFunction. 
I searched through examples and find for instance how to create 'alerts' etc. from 'properties' but struggle how to use them in customizeCellFunction. 
Please note I need this only for flat view.