I would have practiced first, on a "simpler" setup,
to see what the files are supposed to look like.
https://news.aioe.org/
tin -g
nntp.aioe.org
q
*******
I tried the test, and these are the artifacts.
.newsrc
.tin
nntp.aioe.org
serverrc 416 bytes
.oldnewsrc 235 bytes
newsgroups 2,491,479 bytes
If I
mv newsgroups newsgroups.old
then
tin -g
nntp.aioe.org
it downloads a new copy of "newsgroups"
and puts it in that directory.
If the file is a couple megabytes, that means
your E-S is authenticated, if the newsgroups
file is very short (1KB), that means authentication
did not happen.
*******
The full-qualified domain name error, refers to the
local node, and nobody cares about that :-)
Paul