Dim doc As Document, para As Paragraph
Dim lang As WdLanguageId
Dim dict As New Dictionary

Set doc = ActiveDocument
If Not doc.LanguagedDetected Then doc.DetectLanguage
' count languages in paragraphs
For Each para In doc.Paragaphs
   lang = para.Range.LanguageId
   If Not dict.Exists(lang) Then 
       dict.add lang, 1
   Else
       dict(lang) = dict(lang) + 1
   End if
Next
' determine most popular language
Dim maxCount As Integer, maxKey As wdLanguageId
For Each key In dict.Keys()
   If dict(key) > maxCount Then 
      maxCount = dict(key)
      maxKey = key
   End if
Next

Debug.Print "Most popular language is: " & maxKey