The rulebook in Baby Blitz says that the base game rules stay unless otherwise noted in the Baby Blitz rulebook.
That is true. And because of that, rules for german searchlights HAVE CHANGED.
page 6: The new Quick Reference Charts supercede those from the original "Duel" game.
and the new charts say that a single searchlight helps ONE flak and/or ONE nightfighter. Trust the reference cards, they are your only hope.