OK, I see your sample has lots of section breaks and it appears that consistently your right column is content in a section that follows a column break. This pattern could break in a real document if a section continues to a new page but based on your sample, this code works to assign a different language to anything following a column break.
Code:
Sub SetLanguages()
Dim aSect As Section, aRng As Range, lngPos As Long
ActiveDocument.Range.LanguageID = wdGerman 'language for first column
For Each aSect In ActiveDocument.Sections
Set aRng = aSect.Range
lngPos = InStr(aRng.Text, Chr(14))
If lngPos > 0 Then
aRng.MoveStart Unit:=wdCharacter, Count:=lngPos
aRng.LanguageID = wdEnglishAUS 'language for second column
End If
Next aSect
End Sub
If you wanted to work with styles with languages assigned (and you should) you can change
aRng.LanguageID = wdEnglishAUS
to
aRng.Style= "Normal"