The British Library's copy (a photocopy may be ordered by payment to the Imaging Department) gives the song, cited in the OP of this thread, as
"A Lament. For Nurse Cavell."
Words by Murdoch Maclean.
Melody and Gaelic words by Malcolm MacFarlane.
Edited and arranged by Arthur W. Marchant.

On another Mudcat thread, that for poet Murdoch Maclean, I have posted his English text, as it is separately printed on one page of the sheet music from publisher Eneas Mackay.

What follows is a lyric in Scottish Gaelic; it is given only within the sheet-music score, not printed separately. The melody of the song, if the previous citation is correct, was composed and adapted to Murdoch Maclean's lyric by Malcolm MacFarlane.
Elsewhere in the same score, Malcolm MacFarlane is identified by two names:
the first is the previous Anglicized name;
the second says "Fo Laimh Chalum Mhic Pharlain."
Malcolm MacFarlane is also identified as
the author of the Scottish Gaelic text.

In the actual printed music, the melody has its own line of staves.
Directly below it is Murdoch Maclean's English.
Directly below that is Malcolm MacFarlane's Scottish Gaelic, in italics.
The keyboard accompaniment (Arthur W. Marchant, if you are keeping track)
is written out on a "grand staff" directly below the two lines of song text.

If you compare the two poems and their -- what are the words -- prosody and scansion,
it is clear that they differ slightly.
The Gaelic actually has an extra syllable or two per line, compared to the English poem.
The actual tune bears this out.
The melody has been meticulously printed so that the English-text notes are copied out, large and full-size.
In that same melodic line, smaller-sized notes indicate the pitches on which to sing those extra syllables of the Scottish Gaelic.

Deep breath: and let's type out that Gaelic as best we can.

[no separate Gaelic title] [Eideag Chaithbhéil?]

by Malcolm MacFarlane / Chalum Mhic Pharlain

Fann ghaoth na mochthrath ri osnaidhean bròin;
Fairge fo uamhunn, is gruaim air na neòil;
Saorsa, le heagal, air teicheadh gu còs,
'S Eideag Chaithbhéil 'si 'na beuban gun deò.

Gníomh na minaire thug bàrr a thaobh tnùth
Air Herod 's air Néro le'n reubairean gnùth,
Mort na mna mìn thaobh a dìlse 'nar cùis.
Dhaibhsan thig dìoghladh, ach dhìthse thig cliù.

Dìoghlar e mìghnìomh nam mìstearan thall:
Chì sinn ma's beò, gur i chòir a bhios ann;
'S theid cliù na banghaisgich, o dheachdadh peann,
Sìos feadh nan linn gus an crìochnaichear àm.

Sèimh biodh do chadal, a bhanoglach chaomh;
Leigheas nan creuchd b'e do dhreuchd air an tsaogh'l;
'Sluachmhoire t' éifeachd do chreutairean daor,
Ma theagaisg do mhort daibh gur sochair an tsaors'.

No date is printed, but presumed 1917.
Stirling: Eneas Mackay, publisher (43 Murray Place).