As we created RunMags, we set out to create a cost effective platform for magazine publishers. Standardizing the user interface and using ISO date formatting are some of the things we do in order to avoid problems and to keep administration to a minimum - all in order to keep cost at a minimum. Each field that we allow to be "localized" will create more set-up work, more administration and will also introduce a higher risk of introducing software errors.
You will see that we spell with the letter z, dates are ISO formatted, commas are used to separate groups of thousands, and the field used to write down a customers identification with the tax authority is generalized to "Tax id". With that said, we understand the need for some localization of your customer facing documents. That's why, in company settings, you can set if the tax field should say Sales tax, GST or VAT, you can set your currency marker, banking information, etc.
Read this article on ISO 8601 formatted dates.