Italian locale settings break Excel Formulas in my code

I wrote a small Excel COM automation code in Ruby that works on my machine.

Since everything worked fine, I have decided to test it on a client machine.

Only formulas didn't work.

I always get #NOME? for cells that use them (language is Italian).

When I download the Excel file and open it on my machine I get the same #NAME? error.

After searching for solutions, I found only FormulaLocal alternative but I do not like it, I have a bad feeling this is a workaround, not a production-quality approach.

Below is the minimal Ruby code that reproduces the issue (in case it will help someone):

#frozen_string_literal: false require 'win32ole' application = WIN32OLE.new('Excel.Application') application.visible = true workbook = application.Workbooks.Add(); worksheet = workbook.Worksheets(1); # Example input data (replace with your own array) texts = [ 'TEST', '123456ADFG' ] texts.each_with_index do |text, index| worksheet.Cells(index + 1, 1).Value = text end # Make column A width match the widest cell content worksheet.Columns('A').AutoFit dates = [ '2024-09-16', '2024-09-22' ] dates.each_with_index do |date, index| worksheet.Cells(1, index + 2).Value = date end worksheet.Columns('B:C').AutoFit worksheet.Range('B2').Formula = '=ISOWEEKNUM(B1)' numbers = [ 1.35, 2.65 ] numbers.each_with_index do |number, index| worksheet.Cells(1, index + 4).Value = number end worksheet.Columns('D:E').AutoFit worksheet.Range('D1:E1').NumberFormat = '0.00' # using absolute references removes triangle popup in Excel when the formula is entered, # and it also allows you to copy the formula down without changing the reference range worksheet.Range('D2').Formula = '=SUM($D$1:$E$1)' worksheet.Range('D2').NumberFormat = '0.00' worksheet.Range('D3').Formula = '=(SUM($D$1:$E$1) * 1.2)/3.0' worksheet.Range('D3').NumberFormat = '0.00' XL_OPENXML_WORKBOOK = 51 # .xlsx output_path = File.join(File.dirname(File.expand_path(__FILE__)), 'output.xlsx') output_path = output_path.tr('/', '\\') begin previous_alerts = application.DisplayAlerts application.DisplayAlerts = false workbook.SaveAs(output_path, XL_OPENXML_WORKBOOK) puts "Saved Excel file to: #{output_path}" ensure application.DisplayAlerts = previous_alerts end begin workbook.Close(0) rescue WIN32OLE::RuntimeError => e puts "Error closing workbook: #{e.message}" end begin application.Quit rescue WIN32OLE::RuntimeError => e puts "Error quiting Excel: #{e.message}" end # Help Windows release COM references so Excel.exe doesn't linger worksheet = nil workbook = nil application = nil GC.start 

Is there a locale-agnostic approach that works for me?