That check does indeed pertain to decell also.
The problem you are suffering from is generally a fault with the FFG.
Not much to test 11, it either passes or it doesn't.
Take the engines from Flight idle (approach idle) to 95% and time how long itg takes - compare this with the graph supplied.
Decell is even more simple - from 95% to flight idle must be no more than 10 seconds.
Checks are pretty similar for the 535C and the E4 engines.
WAIVER - this is not the entire contents of the check, just an idiots guide.