One of the post-WRE states in the region pushes south from former Mauretania Tingitana into the coastal regions of modern Morocco. Over the next few centuries, the Moroccan Berbers are converted to Christianity, and a significant portion of them end up speaking an African Romance language (although linguistic assimilation will be a longer process).
Probably one of the Romano-Berber states would be the best candidate (although they wouldn't be the best for leading the area to speak a Romance language), but maybe also a Carthage-based state or an Iberian state would work too. In the long term, it's likely a state with borders resembling any of the medieval Islamic Moroccan states would emerge in the region, independent from either Iberia or Carthage.