Not sure if you're open to issue reports on not, specially in the legacy libraries, but I had an issue with your library golib/v2/legacy/localize and was wondering if there's a way to fix this. Consider the following example:

import (
	"github.com/tawesoft/golib/v2/legacy/localize"
	"golang.org/x/text/language"
)

numberFormat := localize.NewDecimalFormat(language.BritishEnglish)
result, err := numberFormat.ParseFloat("1234.56")

numberFormat := localize.NewDecimalFormat(language.German)
result, err := numberFormat.ParseFloat("1234.56")

For English, the result is 1234.56 as expected. But for German, the . is the thousands separator, so result becomes 123456.00. I explored this library and found that group separators are simply ignored. This sort of makes sense, since this separator is superfluous. But In my opinion the number 1234.56 in German should actually be invalid because you can't have just 2 digits after the separator.

I understand you are probably not interested in patching this legacy library, but I wonder if there's at least a way to access the decimal separator externally. It would at least allow me to do some extra validation of the number format beforehand.