Problem with overriding objects on custom size pages

The idea I set forth in my previous post worked well in practice so I'd like to expound on it a little:

The script uses a several templates to create indd-files for different products which are finally exported to pdf (for print).

The script (js) reads the data directly from Excel workbook consisting of several spreadsheets used as a sort of database (vbs called from js) to fill in pages with text and pictures (using labeled boxes).

A spreadsheet has a column indicating which orientation should be used for each page -- landscape or portrait.

The template has two master pages – named L- landscape and P-Portrait – and two 'original' pages: 1^st – portrait, 2^nd – landscape which are duplicated as much as necessary and deleted at the end:

Here's the relative code snippet:

function ProcessProduct(obj) {
    try {
        var spread, page, bylineTextFtrames, pageNum,
        template = new File(templatesFolderPath + obj.product +".indt"),
        pdfFile = new File(obj.pdfExportFolderPath + obj.schoolNameShort + " - " + obj.classNameShort + " - " + obj.product + " - Print Files.pdf");
        
        if (obj.product == "Order forms") {
            pageNum = obj.data.length / 4 - 1;
        }
        else if (obj.product == "Placemat") {    
            pageNum = obj.data.length;
        }
        else {
            pageNum = obj.data.length - 1;
        }
        if (pdfFile.exists && !set.cbOverwriteExistingPdfsValue && pdfFile.length >= pdfSizeLimit) {
            return;
        }
        progressTxt.text = "Processing school: " + obj.schoolNameShort + ", class: " + obj.classNameShort + " (" + countClass + " out of " + countClasses + ") -- Making " + obj.product;
        progressTxt1.text = "Making InDesign document from template";
        
        if (obj.product == "Class order summary") {
            ProcessClassOrderSummary(obj);
        }
        else { // other products
            doc = app.open(template, !set.cbInvisibleModeValue);
        
            if (set.cbSaveInDesignFilesValue) {
                doc.save(new File(obj.inddFolderPath + obj.schoolNameShort + " - " + obj.classNameShort + " - " + obj.product + ".indd"));
            }
        
            var currPageNum = 1; // used only for Placemat  so far
            
            for (var i = 0; i < pageNum; i++) {
                progressTxt1.text = "Duplicating pages: " + (i + 1) + " out of " + pageNum;
                
                if (obj.product == "Placemat") { // Placemat
                    if (obj.data[0] == "P") { // Portrait
                        spread = doc.spreads[0].duplicate(); // duplicate the spread instead of adding a new page because of the bug
                    }
                    else { // Landscape
                        spread = doc.spreads[1].duplicate();
                    }
                    var page = spread.pages[0];
                    var allMasterTextFrames = page.appliedMaster.textFrames.everyItem().getElements();
                    
                    for (var j = allMasterTextFrames.length - 1; j >= 0; j--) {
                        var textFrame = allMasterTextFrames;
                        if (textFrame.label != "") {
                            textFrame.override(page);
                        }
                    }
                    IncrementLabels(spread, obj.product, currPageNum);
                    currPageNum++;
                }
                else { // Other products
                    spread = doc.spreads[doc.spreads.length -1].duplicate(); // duplicate the spread instead of adding a new page because of the bug
                    IncrementLabels(spread, obj.product);
                }
            }
        
            if (obj.product == "Placemat") { // Placemat - remove the first two pages
                doc.spreads[0].remove();
                doc.spreads[0].remove();
            }
                    
            if (obj.product == "Order forms") {
                PlaceImagesOrderForms(doc, obj.imageFiles);
            }
            else {
                for (var j = 0; j < doc.pages.length; j++) {
                    page = doc.pages;
                    imageFile = GetImageForPage(page.name, obj.imageFiles);
                    if (imageFile != null) {
                        PlaceImages(page, imageFile);
                    }
                    else {
                        $.writeln("Can't find the image for page:" + page);
                    }
                }
            }
            var allTextFtrames = doc.textFrames.everyItem().getElements();
            FillInTextFrames(obj, allTextFtrames);
            ExportPDF(doc, obj);
        }
    }
    catch(err) {
        try {
            LogError("Error: " + err.message + ", file: " + doc.name + ", line: " + err.line);
            $.writeln(err.message + ", line: " + err.line);
            doc.close(SaveOptions.NO);
        }
        catch(err) {
            $.writeln(err.message + ", line: " + err.line);
        }
    }
}