You were surprised that 12 people had turned up on time?
Clearly the traffic wasn’t the reason you were late, otherwise everyone would have arrived late!
Also your convoluted reasoning re the restaurant is still unreasonable!
You gave them 14 preorders, which they catered for, you were lucky they could accommodate an unexpected guest.
You sound like someone who finds it difficult to take responsibility for their actions and looks to defer the blame.
If you knew an important guest wasn’t eating for some reason, why not have your meal in a nice gastro pub type place rather than a restaurant?
Organising exact numbers, even if that means chasing friends or crossing them off the list was your responsibility.
Ensuring the restaurant has the preorders was your responsibility.
Getting to the restaurant 15 mins early was your responsibility. Getting there late was the fault of your poor time management, not traffic.
If you had arrived even on time to greet your guests all the confusion you caused would have been smoothed out.
Even if you had arrived late, you should have been full of apologies and explained calmly where the confusion lay and phoned your friend to explain, not try and deflect the blame for the confusion into the restaurant.
Did you tell your friend he’d be able to sit in with you or did he make the same bizarre assumption that restaurants and pubs work the same way?
It feels like you’re someone who thinks the world should work on their terms, and are shocked when things don’t work out or people are upset, or shirty.
Cos you “I didn’t mean to cause any harm!”“ I don’t understand why people are upset with me!” “Everything that happened were completely out of my control!”
When all of this could have been avoided if you had thought it through, planned and communicated with everyone involved effectively.
Perhaps your friend just wants to hear you take some responsibility?