"He speaks with the spiritual world."
Translation:Mae e'n siarad â'r byd ysbrydol.
siarad â is the correct form here but siarad efo is common in the North and siarad gyda is heard in the South.
siarad efo was rejected again just now. Should it be accepted as a common form, or should it be rejected so that we will learn the "proper" form?
It is best to learn the correct prepositions that go with particular verbs to convey particular meanings. After you have been using Welsh for a while, you become familar with the various dialect and register differences.
There is a very useful small book which lists very many of the verb and preposition combinations and their meanings - 'Pa Arddodiad?' (D Geraint Lewis)