Dear Andrea,
Sure, will transmit to the colleagues working on the manual!
Regarding electronuclear interactions, I confirm that with WHAT(2) > 0, one should always see the primary electron in the final state.
Regarding photonuclear interactions, the biasing is achieved slightly differently (no “trick” of adding the primary to the final state), and even with WHAT(2) > 0, the primary photon is guaranteed to never be in the final state.
Hope this helps,
Cheers,
Gabrielle