CSV files are plain-text files, thus, they do not have such an attribute as a language. The only thing that you do in that respect is to control the encoding when you export to CSV, so make sure to tick Edit filter settings in the export dialog. To be on the safe side, choose UTF-8 or UTF-16. For further information refer to the manual.
Here is my macro that exports a spreadsheet to UTF-8, tab-delimited, no text delimiter:
Sub ExportToGlossary
Dim oDoc as Object
Dim glossaryFileProperties(3) as new com.sun.star.beans.PropertyValue
Dim sURL as String
Dim iLen as Integer
Dim isSpreadSheet as Boolean
oDoc = ThisComponent
If oDoc.getLocation() = "" Then Exit Sub
isSpreadSheet = oDoc.supportsService("com.sun.star.sheet.SpreadsheetDocument")
If isSpreadSheet Then
sURL = oDoc.getLocation()
iLen = len(sURL)
If lcase(right(sURL,4))=".ods" Then
sURL = left(sURL, iLen - 4)
Else
If lcase(right(sURL,4))=".xls" Then
sURL = left(sURL, iLen - 4)
Else
If lcase(right(sURL,5))=".xlsx" Then
sURL = left(sURL, iLen - 5)
End If
End If
End If
sURL = sURL + ".txt"
glossaryFileProperties(0).Name = "FilterName" ' setting properties of exported file such as tab as field delimiter, nothing as text delimiter, UTF-8 as encoding
glossaryFileProperties(0).Value = "Text - txt - csv (StarCalc)"
glossaryFileProperties(1).Name = "FilterOptions"
glossaryFileProperties(1).Value = "9,0,76,1,,0,false,true,false"
glossaryFileProperties(2).Name = "Overwrite"
glossaryFileProperties(2).Value = True
oDoc.storeToURL(sURL, glossaryFileProperties())
End If
End Sub