You might try a macro like:
Code:
Sub SetPolishSpelling()
Dim i As Long, j As Long, k As Long
With ActiveDocument
Application.ResetIgnoreAll
With .Range
.LanguageID = wdGerman
.NoProofing = False
For i = 1 To .Sentences.Count
With .Sentences(i)
If .SpellingErrors.Count > 0 Then
j = .SpellingErrors.Count
.LanguageID = wdPolish
If .SpellingErrors.Count > j Then
.LanguageID = wdGerman
For k = 1 To .SpellingErrors.Count
.SpellingErrors(i).HighlightColorIndex = wdYellow
Next
Else
For k = 1 To .SpellingErrors.Count
.SpellingErrors(i).HighlightColorIndex = wdBrightGreen
Next
End If
End If
End With
Next
End With
End With
End Sub
In theory, the above macro should convert each 'sentence' that has more spelling errors as a German sentence than as a Polish sentence to Polish. In either case, any residual spelling errors will be highlighted. One limitation of looping through sentences is that what Word VBA regards as a sentence includes phrases terminated by periods such as you might have after an abbreviation (e.g. Mr., Mrs.). If your German & Polish sentences were in different paragraphs, checking would be much easier and probably more reliable.