Speculation on hand A. Red against white, I suppose that 2

is not based on AQxxxx and zip. Some more shape or strength or something. Letting imagination run wild, maybe

Qxx

void

AQxxxx

xxxx.
Now that's a pretty good hand, maybe too good for a 2

call, but with vulnerability as it is I think it could be so. Some pairs revert to intermediate jump overcalls when red versus white, but I did not see anything in BWS saying they do.
We can make 5

, but I do not have an agreement with anyone that says a 3

call (as with Jim) over East's 2

says "If you have a

void the

Q, and the

AQxxxx then please go on to 5

.
On the other hand, or maybe this is the other other hand, if the opponents go on to 4

, partner will no doubt look at his heart void and figure that if that 3

bid was inviting him to further compete then surely this is the hand to do it with.
Perhaps more realistically, assume partner has a stiff heart. Then the opponents can easily take the first three tricks. But can they make 4

? Maybe, maybe not. We get at most one

, and unless

are 3-3 we get only two spades. Of curse that's in quick tricks, after they get the lead they still have to find ten tricks. If Lho has a 2=2=4=5 shape this might be pretty easy.

xxxx Qx

Axxx KQJxxx

x xx

AKJxx xxx
5

X is one of those rare cases where the red against white sac pays of, -200 instead of -420, there is at least a chance that W, with his stiff

, will alter the old adage to "The five level belongs to me" and bid 5

. Ok, probably not, but maybe.
Of course the hands could also be

xxx Qxx

Axxx KQJxxx

x xx

AKJxx xxx
in which case 4

would have been off 1. That assumes decent defense, but not hard.
Usually, after North's 2

, we expect N to shut up. But Jim's 3

presumably invites further participation. There will be some guesswork involved, but that's bridge. If the opponents have hands such that going on to 4

seems right to them, N can reasonably think "

void very good, stiff

rather good, doubleton

bad. " Well, we can hope.
So I think I am liking the 3

call. It certainly could go wrong, but it could also go right.