https://www.romhacking.net/hacks/1619/

1.) After the events at Thamasa, when the party is reunited:
    * Do NOT rearrange the order of your party members.
    * Do NOT talk to Gungho.
    * Board the airship and let the scene play out.
    * Afterward, go below deck and immediately swap out your party
      members. It doesn't matter who you switch in or out.
    * At this point, the bug is cleared and you can proceed.
    * Failure to follow these instructions may result in a crash.

2.) It is now possible to use the Warp spell to make a quick escape
    from the Fanatics' Tower.  If you do this, however, you'll find
    that your characters are still restricted to Magic and Item in
    battle.  To undo this, simply reenter and then exit the first
    area of the tower that has enemy encounters.