Instead of [VIP] we would like an "icon" in form of ascii or special character, but when I try that i just get "?" in config instead of "»". Could someone tell me what formatting i should use if i want the star as many uses?

"GroupName": "diamond",
"Priority": 3,
"Title": {
"Text": "[VIP]",
"Color": "#B9F2FF",
"Size": 15,
"Hidden": false,
"HiddenIfNotPrimary": false
},

As long as you save the file as UTF-8, should work.

Oh okay, that might be it since I only edited the file in browser. Thanks for pointing that detail out!