Finally, a hack that lets me play this game without feeling actual pain in my chest from all the anger . . .

  However, I cannot get the final magic container in Hidden Kasuto.  The old woman tells me to return when I have seven magic containers, even though I already have them!  I've found every magic and heart container up to this point and have all items.  My levels are 8/8/8.

   Is this a bug, or have I somehow missed something, or done something in the wrong order?  I've tried using both Nestopia UE and FCEUX.

   Thank you in advance!

This gotta be definitely a bug. I also run into the same situation. I have been doing a bit of debugging and found a Game Genie code that would help those that run into the same situation as me:

NYKLGKAE (aka $B444?08:FF)
Basically, I guess that just to keep homogeneity with the rest of the door people, the door person doesn't really check the total amount of magic containers (position $0783) but rather some other memory position that should be synchronized with that value ($079D). This (supposedly  ) synchronised value is then AND with the value of position $F444 in the ROM without headers ($B444 in CPU memory), whose value is 0x08 or 0000 1000 in binary. Only if that operation returns true you would be granted to enter.

For some reason (that if I have time, I will investigate in the future) that synchronization is lost.

In my savegame, the value of $079D is 0xE5 which in binary is 1110 0101, so, obviously, 0000 1000 AND 1110 0101 is false   .

The Game Genie just forces $B444 to return 0xFF or 1111 1111 in binary, so, the comparison is going to be true as long as there is some value other than 0x00 in $079D.