OP,
Years ago we were having work done, including a new shower fitted, and the shower itself was put in the wrong spot and it was a hassle to redo it.
I didn't care and refused to be made feel bad.
The shower was put in an easier spot for them BUT it would bug the hell out of me every day.
Do NOT underestimate how much that post is going to bug YOU.
You need to really reflect on that annoyance.
100k spent and you will bugged EVERY day.
I would not be letting this go.
IMO this is a really HUGE fxxk up, and I would be making it crystal clear that it is up to the architects to fix THEIR mess, but you are not accepting this.
Sending off an email is a good idea, but do not let this go.
Be brave now, because you will bitterly regret not standing your ground and having to live with it.
Be prepared for them to minimise and just want this to go away.
Their lack of apology is outrageous in the circumstances.