The phrase "were undetermined" can be difficult to find an exact antonym for, as the lack of determination implies a sense of ambiguity or uncertainty. However, some related antonyms could include "were certain", "were resolute", or "were definitive". A stronger antonym for the phrase might be "were conclusive", which implies a clear and decisive conclusion or determination. Other possibilities could include "were resolved", "were settled", or "were decisive". Ultimately, the antonym chosen will depend on the specific context and intended connotations of the text.