Neither. The Accuracy of the Bombardement is roll for per C1.732.
" When the German player purchases a pre-game Bombardment, he records a secret Pre-Registered hex for it prior to setup. To resolve each Bombardment, after all on-map setup is completed he places an FFE:1 counter in the Pre-Registered hex and makes an accuracy dr per C1.732 [EXC: maximum extent of error is two hexes]...."
C1.732:
"...Accuracy (1.3) occurs if the Original dr is ≤ 4;..."