Assuming you use the 123 456,78 format, then in the gauges.js script you could try this version of the extractDecimal() function - around line 3320 in my copy
extractDecimal = function (str, errVal) {
try {
return (/[-+]?[0-9]+\.?[0-9]*/).exec(str.replace(',', '.').replace(' ', ''))[0];
} catch (e) {
// error condition
return errVal || -9999;
}
},