The Echo and languages

[CyrilLucifer]

snip

No, no that's not why I ask.

Assumption: Since you've given examples of the Echo translating your speech, if Nabriales has the Echo, his language should undergo Echo-translation.
Conclusion: Moenbryda should be able to understand him, because he directly speaks to her (therefore, resonating with her soul) on at least two occasions. I really do think Cilia has the right of it and in his arrogance he simply does not care for her to understand; perhaps, given his personality, he was actually hoping she would do exactly what she did and attack him.