Terping is tough! You have to hear what's being said, hopefully hear things correctly, know your audience in terms of how to sign (including but not limited to ASL vs Pidgin Signed English or English word order, and at what vocabulary level), and you have to be a thesaurus. And then there are the times when you have to be a linguist in other languages as well. So it helps to have as much information in advance as possible.
And then there are those moments.
I was texting with a supremely capable interpreter who will be terping her church's Christmas program at DPAC (Durham Performing Arts Center, seats 2600). And as she was planning things out she asked me, entirely as an aside, what Noël means. She may be fluent in Spanish, but I took 5 years of French classes and immediately texted back that Noël is French for Christmas. And then furiously typed, using gloss (English transcription of ASL, written in all caps for easy reading on the fly) to hopefully clear things up: Noël means CHRISTMAS, not FRENCH CHRISTMAS. In French, the word Noël translates to Christmas in English.
I can just see her terping FIRST FRENCH CHRISTMAS ANGEL PROCLAIM... (The first Noel the angel did say...) and I would be rolling on the floor in absolute stitches, but at the same time, fully culpable.
It's an awkward song. The angels don't say "First Noël" or "shepherds in fields". That entire first verse is: time (The first Noël/Christmas), subject (the angels), verb (did say), object (was to certain poor shepherds), and location (in fields as they lay). Then location again (in fields), description of interrupted action (where they lay keeping their sheep), followed inexplicably by weather?! (on a cold winter's night that was so deep). And deep, as far as I know, is not even a meteorological term, and is only in there because poetically it rhymes with sheep. Only when you get to the chorus do you hear what the proclamation is: CHRISTMAS CHRISTMAS CHRISTMAS CHRISTMAS! BORN KING ISRAEL.
ASL is pretty. And it is a lot of work to make it so.