You are of course assuming that the coins are missing, even though there has been no proof of that.

Ukyo either stole or lost the coins. In both cases you are fucked. If he stole them, the only way to get them back was probably to bring in law enforcement months ago. if he lost them, he's incompetent, so why do you think he'll be able to get them back or do a "project" to earn that many coins again?