So here's a thought: How about some kind of internal rhyme?
The tune for "Schiarazula Marazula/Maltese Bransle" ends most of its lines with a musical "STRESS-unstress." Rather than try to do end rhyme - which would (assuming I use some of the original language like "ewe") put the rhyme on the unstressed beat - I could do an internal rhyme, so that the "oo" sound falls on the musical stress.
The first verse, ending in "cuckoo," nicely puts "oo" sounds in both syllables. (At least, it does the way I pronounce it, "COO-coo," as in "Cuckoo for Cocoa Puffs." If you pronounce it "CUH-coo," not so much.) My handy online rhyming dictionary isn't finding anything that rhymes with "cuckoo" or "boo-boo," so I'm not going to torture myself into trying to come up with more two-syllable words with "oo-oo" sounds.
In the second verse, "anew" has a nice "oo" sound on its stress; so there needs to be an unstressed word following it. "Spring the woods anew..." Anew what? A new nothing, is the problem. It's an adverb, modifying "spring," which is what the woods are doing. I could cheat a little and change it from "anew" to "a new": "Show the woods their new leaf," "Spring forth the trees their new leaf/leaves." (The second has an extra syllable but the first note subdivides readily.) Eh, they don't really "spring forth" leaves, although they might "send forth."
Seeds all sprout and meadows bloom
Send forth the trees their new leaves
I like "leaves" better than "buds," even though "buds" gets you bonus alliteration with "bloom." "Leaves" assonates with "trees," maybe that's it.
Verse three has ewes in it; "ewe sheep" comes instantly to mind. Now to just reorder the animals in that verse:
Goat and bullock merry frolic
Lamb bleats after ewe sheep
I'm willing to allow "merry frolic" rather than "merrily frolic" on poetic license, I think. Too bad we lose the cow, but it's no longer pronounced "coo" expect perhaps in Scotland.
Verse four reinvokes the cuckoo, which suggests itself for the rhyme again.
Sing all birds and never stop,
Loudly sings the cuckoo
I could do a new last line ("especially the cuckoo," for instance) but I like echoing the first verse this way.
Maltese Cuckoo, Second Draft
Summer is a-coming in now,
Loudly sings the cuckoo
(repeat)Chorus:
Sing cuckoo nu,
Sing cuckoo nu,
Everyone
Sing cuckoo nu
(repeat)Seeds all sprout and meadows bloom, send
Forth the trees their new leaves
(repeat)Goat and bullock merry frolic
Lamb bleats after ewe sheep
(repeat)Sing all birds, your joy unceasing,
Loudly sings the cuckoo
(repeat)
...The first line of verses 1 and 4 needed unstressed syllables, too, so I added some in. I am not very pleased with "summer is a-coming in now," not at all, and I'll be rethinking that. Verse four has moved even farther away from the source material and the language sounds vaguely hymn-like, but it scans well and conveys the right meaning.