Hello,
What is your request?
I want "CFG" module should be located at bottom and be a narrow rectangle.
Here is a proposal, but without big change:
@startuml
skinparam handwritten true
rectangle "APB" as APB
rectangle "POOL" {
rectangle "SRAM" as SRAM
rectangle "PROC" as PROC
card "CFG" as CFG
}
SRAM <--> CFG
PROC <--> CFG
PROC <--> SRAM
APB <-> CFG
@enduml
Or just add '\t' as:

Regards,
Th.