How to get text (word) for a unwanted font in Photoshop Script

So modify the Script. 

You can check for the specific font-name with an if-clause within the for-clause (edited) and use the »from« and »to«-values to determine the affected letters. 

Edit: 

// based on code by michael l hale;
// get letters with specific fonts from selected type layer;
// 2024, use it at your own risk;
if (app.documents.length > 0) {
if (app.activeDocument.activeLayer.kind == LayerKind.TEXT) {
var theFont = "Arial Black";
var ref = new ActionReference();
ref.putEnumerated( charIDToTypeID("Lyr "), charIDToTypeID("Ordn"), charIDToTypeID("Trgt") ); 
var layerDesc = executeActionGet(ref);
var textDesc = layerDesc.getObjectValue(stringIDToTypeID('textKey'));
var theText = textDesc.getString(stringIDToTypeID('textKey'));
var paragraphStyle = textDesc.getList(stringIDToTypeID('paragraphStyleRange'));
var kernRange = textDesc.getList(stringIDToTypeID('kerningRange'));
var rangeList = textDesc.getList(stringIDToTypeID('textStyleRange'));
var theFonts = new Array;
for (var m = 0; m < rangeList.count; m++) {
var thisOne = rangeList.getObjectValue(m);
var aFont = thisOne.getObjectValue(stringIDToTypeID('textStyle')).getString(stringIDToTypeID('fontPostScriptName'));
var aFontName = thisOne.getObjectValue(stringIDToTypeID('textStyle')).getString(stringIDToTypeID('fontName'));
var theFrom = thisOne.getInteger(stringIDToTypeID('from'));
var theTo = thisOne.getInteger(stringIDToTypeID('to'));
if (aFontName == theFont) {theFonts.push([aFontName, theText.slice(theFrom, theTo), theFrom, theTo]);}
};
alert ("\n"+theFonts.join("\n"));
};
};