Imo, I think the trade routes as it is makes more sense for Dumnonia because Dumnonia would start out with a very small, relatively weak culture. It takes time for a culture to spread and become powerful and dominant, history-wise it'd seem more logical that it'd spread around the continent first before travelling overseas.
You could always try giving Cornwall it's own melting pot events similar to what England and Scotland have. Also, you could just increase burgher/nobility power, loot like crazy and let revolts happen there in target provinces, those are also good ways to make culture spread faster.
103;31
103;18
31;18
18;16
64;11
What does this mean, I tried putting it in the file place you suggested but it kept coming up wth 'please chosse another filename'.
I don't understand how I can create a melting pot that exists within England and Scotland... How do you do it and what does it do?