I have a German Christmas song of the 16th century, which is bilingual, German–Latin. The lyrics go as follows (I translated the German parts into English):
O how beautiful the group of angels is singing, praising God for today and forever and sing:
Gloria in excelsis Deo!
They are rejoicing that Jesus Christ has become human in favour of us. That's why they are singing:
Et in terra pax hominibus bona voluntas
So let's be happy too and sing with the angels:
Gloria in excelsis Deo
Clearly, this is an adaptation or even translation of Luke 2:13:
et subito facta est cum angelo multitudo militiae caelestis laudantium Deum et dicentium gloria in altissimis Deo et in terra pax in hominibus bonae voluntatis
My problem in the Christmas carol is the apparently nominative case of "bona voluntas". To my understanding
Et in terra pax hominibus bonae voluntatis
can be translated as
And peace on earth by the humans which are of good will
by the humans is the translation of the ablative "hominibus" and
which are of good will corresponds to the genitive "bonae voluntatis"
But I cannot find a proper translation of
et in terra pax hominibus bona voluntas
Is there a meaningful translation, or is this just wrong or bad Latin in the source?