I have never played it live where players have shown what hearts they have taken. At most, the question "have hearts been broken?" is allowed and a truthful answer must be given. Also, the last trick taken may be revealed at a request before
any other cards are played. But to know how many each person has taken is up to each player to remember. Looking back through past tricks (even the ones I've taken) is expressly forbidden, unless I am accusing someone of cheating (playing off-suit when they could have played the suit).
Since this site prevents that form of cheating, there is no reason to allow looking through the hands to gain that knowledge, and any other information. It is up to the individual to remember what cards have been played. This mimics the live play better.