I'll go phrase by phrase. Here's the first:
In the tenth verse, the text here is "Hither come, ye heavy-hearted." As if to reflect the "heav[iness]," the melody descends at the end.
I didn't find any musical features in the second or third phrases, but I did notice some merisms in the text: "far and near" in the first verse and "great and small" in the eighth.
The fourth musical phrase:
In the eleventh verse, the text here is "Every hand outstretchèd." "Outstretched" is sung with a melisma (F G F), and this expanded pronunciation (indicated by the accent) gives a sense of the word's meaning.
The sixth and seventh musical phrases (combined because they're so short):
In the first verse, the text here is "Till the air / Ev'rywhere." Each syllable of "ev'rywhere" is sung to a different pitch (Bb Ab G), giving a sense of that breadth.
In the eighth verse, there's an-other merism here: "Hail the Star / Near and far."
In the fifteenth verse, the text here is "There on high, / In that joy." "High" is sung to the highest note in the phrase (and even in the whole tune), and this gives a sense of its meaning.
The eighth musical phrase:
In the fourth verse, the text here is "Left His throne above us?" (This completes the sense from earlier in the verse: "Should the Son of God not love us, / Who, to cheer / Suff'rers here, / Left His throne above us?") Pitch-wise, "throne" (sung to an Ab) really is above "us" (sung to an Eb).
