CanPixhawk use the legacy inertial navigation?

From the wiki page it is known that if we left AHRS_EKF_USE = 0 than Pixhawk uses the legacy complementary filter in inertial navigation algorithm. However, the algorithm and its variables are designed for the fast_loop frequency of 100 Hz. We can see that with this definition
then 3rd order estimate (i.e. horizontal position) is stored at 400/10=40Hz. With GPS delay of 400ms, GPS reading should be compared with the historic data stored in buffer 16 samples ago that means the buffer’s size should be 17 instead of 5. Of course it is rarely that Pixhawk needs to use the complementary filter, but if it needs, the software should be modified.