Always good to have a backup plan
I have a book of Christmas carols arranged for SATB crumhorns or recorders. It's The Loux Christmas Collection No 2 published by the Loux Music Publishing Co in New York (who refer to Krummhorns). No idea if it's still available. I've had my copy for years, but never heard the contents played by just crumhorns although I've had a go with various unlikely combinations for fun. It's got a couple of older carols which are sensible crumhorn fodder, but also Jingle Bells and Silent Night for novelty value!
I regret to say that on the back of this book they list other publications, including "Krummy Kuartet for Krummhorn Konsort" by John R Phelps. Groan
Any crumhorn players who might like to get together for an informal playthrough some time, do get in touch - you can send me a PM if you're signed up.
Caroline