As you know decimal separator are different across countries, could be either coma or dot as per thousands separator can also be coma or dot.

Business Central is able te recognize the decimal separator on user input depending the regional setting, but then alway turn it back to coma on display to the internal format (using coma). Changing the default service language does not solve this.

Lot of countries are not using coma for decimal separator so it would be a good thing to have the display of numbers adapted for thoses in Business Central