So, here is your solution tree, since you just decided to dismiss any previous calls for proper corrective action and label them as non-communicative:
1 - You credit retroactively as you should, something that is NOT AT ALL COMPLEX as all you have to do enumerate any cities that have IA buildings in it, take each IA unit in the city and add/subtract the difference between the new and old value to a counter variable, and then add/subtract that total to the owner of the city global ranking points total. More the point, you have done this kind of operations retroactively before, over far more complex scenarios that includes going through a player's log in order to recalculate things.
2 - if you want to label yourself as BETA and keep that label perpetually as a way to excuse your lack of coding and ethical business practices, then you must agree that every diamond spent on an IA unit that we delete prior to the update, something we must do in order so that the rank points lost are the same as the rank points I PURCHASED WITH THE DIAMONDS YOU SOLD ME, will be credited to my Diamonds balance. Not an ideal solution as there will be a number of hours, unknown at this point, in which we won't be collecting supplies or cons from lost building, and happiness will be severely affected on any other units that can still produce. This will also affect the player's city defenses and offensive capabilities. For this reason rank points should be credited for this by calculating the MEDIAN number of points a player produces per day over the last 7 days and adding it to their global ranking. Why not an hourly pro-rate? Because most players produce most if not all of their points over a relatively small number of hours.
3 - Do nothing and continue to antagonize an ever smaller number of hard core players. It won't take long before you will be applying for some German Welfare as the number f players that will keep playing this game are those that have zero interest in ever giving you so much as 1 euro. This might just get me sufficiently fed up with all the BS I have had t bear playing a game I only play because my family also plays it and take the spare time I waste on this **** and get players, litigators and district attorneys all into what it takes to put arrogance like the one you are displaying in its proper business context and place.