My problems occur when TRANSLATE-INTO-FOREIGN-MEMORY is called on an array which is an element of a foreign struct type.

The problem come from :

value is expected to be an array but it is a SB-SYS:INT-SAP in my case.

Unfortunately change its definition to:

(defmethod translate-aggregate-to-foreign (ptr value (type foreign-array-type))
   (loop for i below (foreign-type-size type)
         do (%mem-set (%mem-ref value :char i) ptr :char i)))

Doesn't work.