Hasham, it's perfectly fine mate. It happens. Don't worry. Yes, let us hope we get the speedometers we want. :).
I'm sorry I'll have to disagree where you say that the ECU's would be the same. Although the engines are the same Dual VVTi's, the other functions inside the cabin differ greatly and it is because of these that he pulse sent to the gauge cluster are received as being invalid and trigger an error code and sounds the beeping and the warning lights. An Altis ECU and the Speedometer Grip has ELEVEN extra wires which the GLi and XLi variants do not.
From what I've experienced of the last few days, speedometers from Pakistani variants are compatible with all models despite the fact that GLi and XLi lack the extra eleven connections unlike Altis - hence this speedometer working like a charm in an Altis.
I'm not sure if an Altis Speedometer would work in your Automatic GLi but it definitely does in a Manual GLi and XLi. I put my Uncle's in my car and it worked perfect with no alarms and triggers and Azeem installed his Altis speedometer in a 2010 XLi for a little while to check and that worked perfect too.
Whenever you're back, call me, you've got my number, I'll bring over my Uncle's Altis and we could put that speedometer in your car to check its compatibility with your Automatic GLi. If it works, you then go ahead and find one. If not, well at least you will not be wasting your time.