Where is this reddit post may I ask? Because I can't seem to find it anywhere no matter how hard I search.
Viewing post in Ace Attorney Turnabout Creator comments
IDK about Reddit, but they also address this in the pinned comment of the YouTube video at the top of the page. Basically, they want to have custom characters eventually, but it won't be at launch. Other custom files, like backgrounds and items, should be available before custom characters are, though.