I guess it depends on how much debugging output you want. Since all of these calls go through one function (gettext_printf), you could modify that function to print or log the translated string that gets passed to printf and the corresponding untranslated string.

It would probably be simpler to just log everything from every call to that function and sort it out later.

Something like

gettext_printf () {
  gettext_printf_format="$1"
  translated_printf_format="$(gettext "$gettext_printf_format")"
  shift
LOG $gettext_printf_format and $translated_printf_format HERE
  printf "$translated_printf_format" "$@"
}

Then you correlate these messages to the error you're seeing.

It's not clear why, but it appears that printf is being handed a format string that looks like `%$' and is printing an error because it doesn't understand it. The builtin printf does not display unrecognized format characters; they are errors.

I was trying to see why os-prober from GRUB does not work and I noticed the below error:

---

with LANG=tr_TR.UTF-8
/etc/grub.d# pkgdatadir=/usr/share/grub ./30_os-prober
Uyarı: os-prober will be executed to detect other bootable partitions.
Its output will be used to detect bootable binaries on them and create new boot entries.
/usr/share/grub/grub-mkconfig_lib: satır 288: printf: `$': biçim karakteri geçersiz
/etc/grub.d# LANG=en_US.UTF-8 pkgdatadir=/usr/share/grub ./30_os-prober
Warning: os-prober will be executed to detect other bootable partitions.
Its output will be used to detect bootable binaries on them and create new boot entries.
Found ELILO Boot Manager on /dev/nvme0n1p1@/EFI/elilo.efi/elilo.efi
menuentry 'ELILO Boot Manager (on /dev/nvme0n1p1)' --class elilo --class os $menuentry_id_option 'osprober-efi-AA0B-7A33' {
insmod part_gpt
insmod fat
search --no-floppy --fs-uuid --set=root AA0B-7A33
chainloader /EFI/elilo.efi/elilo.efi
}

---

I'm uploading the scripts as they are all free software.

/etc/grub.d# LANG=en_US.UTF-8 bash --version
GNU bash, version 5.1.16(1)-release (x86_64-slackware-linux-gnu)
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.