Well, I'm going to be up all night over this, I might as well b*tch about it a bit.
NOW (about 02:00 Sat morning) Parcelforce tracking says
20/10/2018
18:12 STN Arrived in destination country . Note the time (18:12 on Saturday the 20th - basically 16 hours into the future!)
The stamp that was 20/10/2018
00:17 STN Arrived in destination country has now changed to 20/10/2018 0:17
STNExported from the UKNow, over on the FedEx side, it says 20/10/2018 - Saturday 00:22
In transit STANSTED GB .
So, I can only hope that it's on the way to Ireland now, and not sitting in Stansted, GB.
I have filed complaints with every possible entity I could find on this. I am especially annoyed that the Post Office insists the problem is Parcel Force and Parcel Force insists the Post Office goofed. And FedEx says they are BOTH wrong.

Holy Frijoles, I'm glad I'm not waiting for a shipment of antivenin!!!!
Edit Saturday morning -FedEx tracking - 20/10/2018 - Saturday 07:19 In transit STANSTED GB
ParcelForce Tracking - no change from earlier. I assume it's cleared customs and is sitting in a big bin somewhere in England.
Phoned ParcelForce a few moments ago to ask if they could see exactly where the documents are. I got someone in India who couldn't do more than read what's online. Referred me to FedEx. Phoned FedEx. Got someone who said I needed to talk to "the international team" who doesn't work weekends, domestic team can't tell me anything about where the documents actually are. Couldn't be arsed to look in their system.
Wow, it just keeps getting worse.

Dropped off a tracked letter to the Irish Govmt at the Post Office this morning (our local one) when it opened. The PO Lady there was horrified, checked and saw in the system that the PO I used was within the zone where the documents absolutely should have gotten to Ireland by yesterday. She ~was~ very nice, and gave me phone numbers to call to complain - as if that will speed anything up? The Foreign Team, after all, doesn't work weekends.

She said the tracked letter might make it by Tuesday as it'll go out at noon today. At least it's sent. There's nothing else I can do.
I see several hundred pounds evaporating, and having to do this all again in my future. A kicker - I sent the Daughter to make copies of everything in the formal application immediately before it went out. Instead of making paper copies, she used the Uni's library copier that was supposed to send it to her email address. She didn't check to see that the transmission went through. It never arrived. I didn't know that until after the application was on the way across the water. So I don't have copies of anything. We'll have to get all the notarized documents re-notarized, as they are now more than 60 days since being notarized and that's outside the allowable window. After I get copies of them all again.

The Daughter needed a third character witness to sign the re-redone application, and didn't want to "push" anyone, so dawdled for over 30 days after the application was ready to go before she got someone else to sign off. One of her other witnesses is now critically ill and may or may not be around long enough to serve as a witness....
Hopefully they'll return everything so we don't have to do the like 30 page application document again.