What an interesting subject. I haven't tried to learn a Cajun song for a long time, but the Big Nick approach is close to mine. I hand wrote phonetically and underlined the words/syllables needing emphasis. I'm a trucker, so I have plenty of time to sing without annoying or alarming those around me.
I too think it's important to know what the song is about, but have to learn parrot-fashion, rather than translate as I sing.
But there's a snag. It's often said that Cajun music should come from the heart, and I guess that goes for words as well as music. So those of us who don't know French that well have a problem. If we're singing parrot-fashion how can it be from the heart? Maybe we should be singing in English or Dutch or German. But it's hard to make it sound authentic in your own language ( if that isn't Cajun French ). Funny enough, though, it can sound OK in another language that you don't know. I heard a Welsh band called 'Cajuns Denbo' who sing in Welsh. It sounded OK to me.
For me i can only remember lyrics if there is some sort of a "story" and can imagine pictures sort of, like a drunkard coming home in Blues du Soulard, or some lovesick idiot hiding in thorny bushes. But i speak a little French, learned from my parents & school, and later by having to deal with bakers, camping owners, gendarmerie, even vets and checkout girls traveling in France.
BJ, great remark; my aunt's now deceased parrot could speak Dutch, and one also understood what the bird said. Though I always wondered if it knew itself what it just said. Probably had humor too and showed some intelligence: When it said "koppie krauw", meaning scratch my neck, and bended it's head before you actually attempted to scratch it, you risked your fingers: sometimes it suddenly & sneakily aimed for them ... - Nout