@dsturnbull: Sorry, but I haven't tried this game with Mac. I am planning on a new version pretty soon, so stay tuned. If there is anything that I can do with packaging it better for compatibility, let me know please.
@Slaxl: I'm not so sure about culture penalties. It's sort of one size fits all the -10 penalty. I thought of tweaking that down but upping the wrong religion group penalty (i.e., for pagan Franks ruling over Christian Bretons). I'm not sure. Let me know what you think.
Coming up with a separate name list is a bit of a chore as neondt said. I might just copy the Saxon one and put down some variants. If you want to work on an Angle culture file, I'd be more than happy to implement it.
I'd forgotten about the opinion penalty... I really don't think an Angle would inherently distrust someone because he was a Saxon. A -5 penalty at the very most I'd say. Vanilla CK2 includes "Frankish" and "Italian" in the lowest level of cultural distinction. By that standard Angle and Saxon are the same culture. As you said before, it's probably best to keep culture simple. If you are going to split them up, it might be a good idea to reduce opinion penalties for characters in the same culture group.
Just a thought, but how about actually reducing the wrong religion group penalty? By about half maybe. To counter that, you could increase the opinion penalty for the zealous trait (by however much you reduce the base religion penalty), and write an event that makes it more likely for a character to become zealous if his liege is of a different religious group. My understanding of the Christianisation of the Anglo-Saxons in particular is that most people weren't all that bothered by their leader being of a different religion (applies for both 'Christian' realms where rulers lapse back into paganism, and pagan realms where the ruler converts), unless they happened to have the real life equivalent of the zealous trait. There were certainly reactionaries when a ruler tried to convert his subjects, but that's about as far as it went in terms of religious hatred. I certainly wouldn't equate it to the enmity between Christians and Muslims during the Crusades, which is presumably what the vanilla relations penalty is designed to model.