Event Hacking question

At the dialogue Where Setzer uses the term 'Ante Up'. So in CB/221F i inserted B2 30 02 27 FE (to move to more space in F1/0230) over top of 94 5A 08 5C D9.

I think you need to look at your starting point again. What you listed (94 5A etc) starts at CB/2221, not CB/221F.

Additionally, call instructions are four bytes, while you have five. The FE at the end is a return instruction, so I guess it could be intentional, but you may need the rest of the event to execute normally, so you can probably remove it.

In F1/0230 I put 94 5A 08 5C D9 because I had written over with the subroutine. Then I added D07E D4 ED D4 FD to add Umaro.

The problem here is that what you overwrote earlier ends with an incomplete instruction (D9 is a two-byte instruction). If you get rid of the trailing FE I mentioned above, you don't have to worry about including D9 in this part.

Don't forget to include an FE at the end of your custom event so the game knows where to go next.

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.