When I came to generate the iso, I got:
(yeah, I had forgotten to set export NUTYX_TMP=/mnt/nutyx_tmp so that stuff ended in my home directory)
root [ /home/paul/packages-x86_64/x86_64 ]
# bash rolling/scripts/mkiso
something went wrong: It's not the 5.3.7-NuTyX kernel in this ISO
root [ /home/paul/packages-x86_64/x86_64 ]# ls $LFS
bin dev home language.check lib64 mnt pkg root sbin sys usr
boot etc ISO lib locale.check opt proc run srv tmp var
root [ /home/paul/packages-x86_64/x86_64 ]# ls $LFS/boot
config_64-4.19.80-NuTyX-lts kernel-4.19.80-NuTyX-lts
grub kernel-lts
initrd-4.19.80-NuTyX-lts System_64.map-4.19.80-NuTyX-lts
root [ /home/paul/packages-x86_64/x86_64 ]#
indeed, it seems to be 4.19.80, not 5.3.7 kernel... is it really wrong?