Curious where you read the polarity spec as center positive?
The 8800 is a simple parallel adapter, which simply combines two CIOKS channels, while maintaining the standard channel polarity; which is center negative AFAIK.
Maximize your pedalboard's power with the Parallel Adapter Flex, designed to combine outputs for increased current from CIOKS power supplies. Perfect for high-current pedals, ensuring stable and efficient performance.
cioks.com
I have the 8800 on 3 boards powering a More, a PMLE, and a Venus Z.