Which terminators are elidable?

lo manku poi co'i klama to'o la midju terdi xamsi co'a gacri lo noi xebni be lo prokuratoro vau tcadu The darkness that came from the Mediterranean covered the hated by the procurator city.

Why are we allowed to omit a separator after the relative clause poi co'i klama to'o la midju terdi xamsi ends?

Here we don't need to use cu before co'a since after it a new selbri (gacri) follows. Since a bridi can't contain more than one selbri we automatically assume that a bridi just ended so we start a new one.

A preposition (co'a) placed before a selbri modifies that selbri. Thus co'a also belongs to gacri.