I found the score again, so I will comment on that final 'amen' for you.
Here is the link
http://conquest.imslp.info/files/imglnks/usimg/9/95/IMSLP58786-PMLP36585-Liszt_Musikalische_Werke_5_Band_6_23.pdf
The piece is all very beautiful and ethereal; the piano intervenes rarely to "seal" the cadences, and at the end after "nunc" and "et", which are wonderful because they are used in an almost percussive way, on "hora mortis" there is this wonderful B45-35-Bm movement, which progresses on "nostrae" with C#45-35-C#m. In my opinion, it is difficult to find a closing, especially considering that one should return to the major key. But he finds it through the procedure used in the progression, i.e., a descending degree movement, which is just the single note in the bass on the syllable "a" of "amen". But since Liszt is Liszt, and uses contrapuntal procedures to create harmony, he actually transforms the very sad C#m into an A7, by subordinating a third (and making the G# descend to G, obviously). The 'amen' simply does A7-D, but the piano returns with Bm46 and then D again.
The whole piece is harmonically very interesting.
It begins in D; on "benedicta" it begins to move towards A, a cadence on A at "mulieribus", but at "ventris tui" he does this illuminating thing, a suspended cadence A6-C#, which leads to two unisons, one on "Je" and one on "sus", C# and F#. Which would seem like a nice return to D.
Obviously not, because the second part continues the ambiguity on F#m (which would be the minor subdominant of the major tonic...), actually following the notes of an F#-A-C#-D arpeggio. "Ora pro nobis" is a beautiful modulating bridge that will lead us to the Em of "nunc", passing through its dominant. With a very beautiful pattern, among other things, because it complicates by varying the previous one. If that was F#-A-C#-D, this is (B) D-F#-G, with more dissonances (the D and G often become augmented triads), and the usual final subdominant of thirds (the B, dominant of Em, alternates with a D#dim7, effectively forming a kind of broken ninth chord).
Sealing this dissonant passage with a very simple alternation of major and minor chords is pure class :-)