I started watching D Gray-man today and I saw the episode with Lala's song. It's so sad. T-T This is sort of like a little tribute to her. Here's the english translation of the song:

Tearful that day,
On which will rise from ashes
Guilty man for judgement.
So have mercy, O Lord, on this man.
Compassionate Lord Jesus.

Yes, the song is in Latin. Here's a link to it:

http://www.youtube.com/watch?v=d2l2Zv1I_Fw&feature=channel_page#watch-main-area