Just found a pretty serious bug in the General Leo Edition hack, which will be corrected in Version 1.1.
General Leo joins the party when they return to the airship after the events at Thamasa. Here's the thing... to get Leo to appear, when you are prompted to "Find the Floating Continent," "Lift-off," or "Not just yet," be sure to choose "Not just yet." This is what actually activates Leo and adds him to the party. If you don't do this the first time... then Leo won't join in the World of Balance.
I am so sorry that I didn't catch this! Again, it wasn't my intention to do it this way, and the error will be corrected in the next release!