Hello, I'm curious if there was a particular reason to lc the resource record data; from import/Base.pm:

my %request = (
    nt_zone_id => $p{zone_id},
    name       => lc $p{name},
    address    => ($p{type} eq 'NAPTR' ? $p{address} : lc $p{address}),
    type       => $p{type},
);

I simply removed the lc in my copy of nictool, but I'm worried there may have been a reason for that which I've overlooked.

The reason I removed it is because it is lowercasing TXT records, and DKIM data, for example, is case-sensitive.