Event Hacking question

In the level editor in the blackjack i moved umaro to 9,8 and set his event to 1E8F6 and 'If mem set' to 1E8F and the bit to 6.

This also won't work, but probably won't matter if you can't talk to Umaro. If you can, his event needs to go somewhere relevant, rather than the middle of some other event which will likely crash the game.

The bit ('If mem set') you're using for him is fine.

If he wants to use that event bit for the Umaro that shows up during the event, then he needs to use another bit that is already set and is going to be cleared. Using 1E8F bit 6 will not allow him to show up until after the scene because it's not set before the map loads, and even if he were to set it first, then the Umaro would stay there even after the event, and there is already an instance of him in the blackjack main room, meaning there would be 2 Umaros.

I would suggest finding an unused bit in the ff6_snes_event_bits.txt Setting it before you load the Blackjack scene, then at the end of your custom code, clearing it so that instance of Umaro is present ONLY during the event.