The bidding went
Having only Passed throughout the Auction, can the Insufficient Bid now be Pass?
Would that be comparable showing no points previously?
1st of all - opponents can accept it - and the auction continues without further rectification. - Law 27A
2nd - the IB can be corrected to 4H (assuming 4H is the lowest call that shows hearts) - again without further rectfication, but if the opponents are found to be damaged then an adjusted score can be made - Law 27B1a
3rd - Assuming that 3H actually shows hearts then pass would not be a comparable call, since that does not show hearts and Law 27B2 applies: Partner will be forced to pass for the rest of the auction, lead restrictions may apply and also law 72C applied (the old law 23 - if a player could have known the IB could work to their advantage then an adjusted score is made - I paraphrase) -