Kyrylics? app.doScript() issues.

Hello, dear community!
I have a trouble running my scripts, using another script for it. They all work, when I run them manually, but some of them do not even start to run, when i use my script. I suppose that the problem should be in kyrylics. I am not 100% sure, but all the scripts are pretty similar and only the strings in GREP find/change change. 
The path is correct, the ecoding is UTF-8 (without BOM), the scripts without kyrylics run both ways and with it only manually. What could be a problem?

function runScriptRunner () {
    // Define the scripts folder (relative to InDesign's Scripts folder)
    var scriptsFolder = ""
    
    // List of scripts to run (relative to the Scripts folder)
    var scriptList = [
        File(scriptsFolder + "1Character styles\\dont_change.jsx"),
        //File(scriptsFolder + "1Character styles\\generate_character_styles.jsx"),

        File(scriptsFolder + "2Extra spaces\\extra_spaces.jsx"),

        File(scriptsFolder + "3Punctuation\\dashes.jsx"),
        File(scriptsFolder + "3Punctuation\\quotes.jsx"),
        File(scriptsFolder + "3Punctuation\\nested_quotes.jsx"),
        
        File(scriptsFolder + "4Nonbreak spaces\\spaces_after.jsx"),
        File(scriptsFolder + "4Nonbreak spaces\\spaces_before.jsx"),
        
        File(scriptsFolder + "5Cornercases\\adpositions_and_conjunctions.jsx"),
        File(scriptsFolder + "5Cornercases\\date_month.jsx")
    ];
    

    // Iterate through the list of scripts and execute them
    for (var i = 0; i < scriptList.length; i++) {
        var currentScript = scriptList[i];

        // Check if the script file exists
        if (!currentScript.exists) {
            alert('Script not found at "' + currentScript.fsName + '".');
            continue;
        }
        else {
            try {
                alert("Running script: " + currentScript.fsName);
                app.doScript(currentScript, ScriptLanguage.JAVASCRIPT, [], UndoModes.ENTIRE_SCRIPT); // Execute the script inside InDesign
            } catch (error) {
                alert("Error running script: " + currentScript.fsName + "\n" + error);
            }
       }
    }
    alert("All scripts executed.");
}

// Run the script runner
runScriptRunner();

Here is an code example which does not run:

function performGREPFindChange(findWhat, changeTo) {
    // Clear previous GREP find/change preferences
    app.findGrepPreferences = NothingEnum.nothing;
    app.changeGrepPreferences = NothingEnum.nothing;

    // Set new GREP find/change settings
    app.findGrepPreferences.findWhat = findWhat;
    app.changeGrepPreferences.changeTo = changeTo;

    try {
        // Perform the Find/Change operation
        app.activeDocument.changeGrep();
    } catch (e) {
        alert("Error: " + e.message);
    }
}

performGREPFindChange('(\\d+)\\s*(січня|лютого|березня|квітня|травня|червня|липня|серпня|вересня|жовтня|листопада|грудня)', '$1~S$2');