Look at the text. Does it seem appropriate?

Hark how the bells, sweet silver bells,
All see to say, throw cares away.
... etc.

There are alternative versifications, such as this popularized....

https://www.youtube.com/watch?v=Hckgu3EWvC8

Why, Chonak, would the English of a devotional service of Lessons and Carols be of no import? Whatever we sing before the altar of God must, regardless of the language, reflect his glory and express the faith of the Church. Why would this be different in an EF parish?

As to the 'sweet silver bells [which] all seem to say, throw cares away' - I think that Mad's rejoinder is, at second glance, not as apt as it might appear. There is quite a difference between bells which 'say' to 'throw cares away' and the hymn from the Liturgy of St John Chrysostom's bidding us to 'lay aside all earthly cares'. The focus is cute charming silver bells versus our personal inner act of faith.

I think that both the text and the cute secular bounciness of the music should 'All seem to say' 'don't sing this in Church'. This immediately-recognisable-as-profane song would be an affront to the altar of God, and to the nature and purpose of Lessons and Carols.

The original lyrics for the tune were from a Ukrainian New Year's Carol "Shchedryk" (which I've sung and also heard, in Ukrainian) ... the English lyrics known today are by Peter Wilhousky (1936). Here is the Ukrainian original and an English translation (non-poetic):

Щедрик щедрик, щедрiвочка,
прилeтiла ластiвочка,
стала собi щебетати,
господаря викликати:
"Вийди, вийди, господарю,
подивися на кошару,
там овечки покотились,
а ягнички народились.
В тебе товар весь хороший,
будеш мати мiрку грошей,
В тебе товар весь хороший,
будеш мати мiрку грошей.
Хоч не грошi, то полова.
В тебе жiнка чорноброва."
Щедрик щедрик, щедрiвочка,
прилeтiла ластiвочка.

Shchedryk, shchedryk, a shchedrivka [New Year's carol];
A little swallow flew [into the household]
and started to twitter,
to summon the master:
"Come out, come out, O master [of the household],
look at the sheep pen,
there the ewes have yeaned
and the lambkins have been born
Your goods [livestock] are great,
you will have a lot of money, [by selling them].
If not money, then chaff: [from all the grain you will harvest]
you have a dark-eyebrowed [beautiful] wife."
Shchedryk, shchedryk, a shchedrivka,
A little swallow flew.

So it was a New Year's song; then, in the American version, it was made into a light Christmas song, retaining its bouncy little folkish melody.

It reminds me a bit of the Renaissance carol Gaudete: not really a beautiful song or fine poetry, but a bouncy little tune set to light Christmas lyrics -- though the Latin lyrics are better than the English.

I'm planning on Christmas Matins next year - there's a fair amount of work. Last time we sang it (about 4-5 years ago), we started rehearsing in April. On the other hand, that is full-tone for all responsories, the Invitatory, etc. so there might be less practice needed if you are taking shortcuts for the various chants.

If it were me, I wouldn't tackle it at this point in the year for this Christmas with any expectation of having a smooth and generally well-done Office unless there were some major rehearsal hours I could throw at it, even if I were doing a simpler version. I certainly second the suggestion for future use, however.

If you need booklets, we had them created for the last time we sang the Office, and they should be available via Amazon or Lulu... let me know and I can get you more specifics. They were beautifully set by one of the members of my current group.

Other resources:
Adaptation from the Liturgical Year: http://www.salvemariaregina.info/SalveMariaRegina/SMR-166/Christmas Matins.html
CD of Matins for reference: https://www.chantcd.com/index.php/Divine-Office-of-Matins-Christmas-Eve