I still don't think the epitaph itself means human sacrifice.... (as I stated in that [Anime] Umineko - Speculation & Theories for first time viewers)
By ep 1-3....
Therefore the epitaph likely means something else.....
What is it ? Trees? No. River. not possible. Statue? Maybe. Could even be Beatrice portray
How about a Japanese character? A character can indicate certain place/ coordinates to where the gold is.
I have 0 knowledge in Japanese Kanji so can't attempt anything. "Kill" and "gouge" and "those who are close" make sense if it means stroke of certain characters. "Key" could means a certain "keyword". But then the "twilight" and "the witch shall be revived and none shall be left alive" makes little sense.....