So after about three weeks I got a response to my pushback on compensation and expenses. No dice on the compensation, and they said their limit on the hotel is £500, but they would consider additional amounts for meals, transport and phone calls. I had included those in my original request, and their original response suggested the £500 limit was for all expenses, but I thought I'd update the case and specify the additional expenses.
Only to be foiled by BA's IT department. They have a dropdown for you to select the currency in which an expense is denominated, but they don't have a choice for Israeli shekels. Obviously most of our expenses in Israel would be in shekels.
So I selected GBP and added a note that those expenses are really in Israeli shekels. We'll see what happens. Maybe I'll get lucky and their bot will treat them as pounds and I'll get a windfall.