You are right about the torpedoes.
The rules for leech torpedoes don't explicitly state that
no to hit roll is needed, so they probably need a hit as well.
Fire ships, rare granted, but you can't BFI versus their effect. The FAQ2007 only allowed BFI to criticals from H&R attacks.
... which brings me back to what I was pondering about ...
I would still like to see this rule addition dropped if H&R attacks are handled differently versus escorts.
The original rule is: BFI doesn't protect against critical damage. Plain and simple but tough on the escorts. To help them out BFI was allowed versus H&R and I agree it was needed. But now another rule is proposed to remedy the same problem.
Why have two special rules when you can do it with just one?
If a 4+ for H&R is still too hard on escorts (I doubt it) 5+ surely will do it.
For comparison:
A single bomber attacking an escort (5+ armor, 1 turret) has a 2/3 chance of killing it if he's not shot down and the escort is not on BFI (someone did the math on another board).
A single assault boat now has a 1/2 chance after surviving turret fire. BFI would reduce this to 1/4.