Here's the original, as published in "The Heir of Abbotsville," by Edward Mordaunt Spencer (London, 1846), p. 83. In his Preface, dated "April, 1846," Spencer says nothing about the inspiration behind the poem. In fact, he doesn't even mention it:

                         THE ROSE OF TRALEE.
(Set to music by Stephen Glover, and published by C. Jeffrey, Soho-square.)

The pale moon was rising above the green mountain,
The sun was declining beneath the blue sea,
When I stray'd with my love to the pure crystal fountain
That stands in the green sylvan vale of Tralee.
She was lovely and fair as the fresh rose of morning,
Yet 'twas not her beauty alone that won me;
Oh no, 'twas the truth in her eye ever dawning
That made me love Mary, the Rose of Tralee.

The cool shades of ev'ning their mantle were spreading,
And Mary, all smiling, was listening to me;
The moon through the valley her pale rays was shedding,
When I won the heart of the Rose of Tralee.
Though lovely and fair as the fresh rose of morning,
Oh 'twas not her beauty alone that won me.
No, no, 'twas the truth in her eye ever dawning,
That made me love Mary, the Rose of Tralee.

To make it still more fascinating, John Brougham's completely different song of the same name appeared in the Columbian Ladies' and Gentlemen's Magazine (March, 1845), an American publication, as part of a short story called "The Blarney Stone."

I can't find any 19th century printings of the stanzas about India. FWIW, the line "I'm lonesome tonight" sounds pretty modern. I think the Victorians would have said "lonely" and something other than "tonight." After all, the point is that he's always lonely, not just tonight.

Just my impression after decades of reading that kind of thing.