Beatrice is, of course, named after the dead lady Dante wanted to do. This is very suitable, since she is the dead lady Kinzo wants to do. There are various references to the Divine Comedy sprinkled throughout Umineko besides that, though.

Rue is both a verb meaning sadness and a poisonous plant, but I doubt the people who named her knew any of this. She actually named herself, after the last syllable of kureru, the Japanese pronunciation of her other name, Kraehe. Which means crow in German.