Corruptors have 29s build time to 64s of Carrier’s, and Protoss player usually won’t construct more than 4 carriers at the time. Decreasing cost of corruptors would in my point make carriers useless, by making corruptors free win button in such case.
Also I have no idea where you took numbers from. Corruptors hard counter ALL protoss air units in terms of supply efficiency with low level micro and their worst match up is vs mass Void Rays, which they win regardless, if Prismatic Aligment is dodged.
On first attempt, for not doing it for months, I repeated your scenario and had 47 corruptors left, so you do something significantly wrong. Check video in linked post for inspiration.
Yes, High Templars are huge in such fight, but it does not seem to be purpose of the thread, and you can add a few ultralisks to the comp for HTs sniping, while having lower supply than Protoss.
You may find some inspiration there: