@IamtheEmps
The thing about that though is that the romanization of Britain was less thorough than the rest of western europe, despite having been under the Romans since the first century. Most of the island was a Roman frontier, always threatened by barbarians, and a frequent source of usurpers. The most romanized parts where in the South East, a place that has now become ruled and at least partially settled by germans.
And as mentioned above by someone else, Latin was a mostly used in urban areas and by elites. Enough to leave an impact for sure, but in this scenario not enough to make it a romance language.
And also, technically there aren't more celtic language's in this scenario anyway, it's actually one short, with "cornish" and "welsh" merging into a single language. I'm not sure Breton would even survive in this scenario, with fewer elites fleeing to Armoricia, and likely a few returning to Britain, in which case that's 2 fewer celtic languages.