As far as I can tell, there is nothing significant about 2012-12-16.
The original release of commentfaces (using the `/` syntax) came on
2011-07-26:
https://old.reddit.com/r/anime/comments/izxos/comment_faces_for_ranime/

The commentface refresh to use the new syntax and introduction to
several more faces occurred on 2015-02-13, but gununu and 17 others
predate that and consequently the introduction date should reflect that
accordingly.

…he readme

The actual date for the early 2016 comment face removal is uncertain, so
I decided to move forward with 2011-03-21 for the following reasons:

1) The comment faces page
(https://old.reddit.com/r/anime/wiki/commentfaces) says early 2016.
2) The retired comment faces page which contains the data for the
screencap for the comment faces page was last updated on 2016-03-14.
3) Archives from the wayback machine on and immediately after that date
still contain the old comment faces.  The earliest archive I can get to
resolve from there with those faces removed is 2016-03-29.  The last
archive I can get to resolve from there still containing those faces is
2016-03-18.
4) The removed date is after the date that the new faces were announced
and presumably provided (2016-03-21 -
https://old.reddit.com/r/anime/comments/4babw1/new_comment_faces/).
5) I'm presuming that the announcement date for the new faces aligns
with the removal date for the old ones in order to have space for the
new ones in the first place and also to provide the smoothest transition
between them.

I'm agreeing with the discontinue date of 5 April 2017 since the
removals wiki page's last edit for the series of edits related to that
purge was on 4 April 2017 so it's feasible enough to me that the actual
turnover date was the next day.

of just ${name} because names are not necessarily unique across
commentfaces (see pointandlaugh or the masked faces).

Ran `awk -F, '{ print $1, $16 }' ../../comment_face_list.csv | while
read name date; do if [ -d "$name" ]; then rename
"s/.*/${name}_${date}/" $name; fi; done` to rename directories that were
in the PWD and `awk -F, '{ print $1, $16 }' ../../comment_face_list.csv
| while read name date; do if [ -f "$name".* ]; then rename
"s/(.*)\.(.*)/${name}_${date}.\$2/" $name.*; fi; done` to rename files
that were in the PWD.

…king things not behave right