Sorry, but there's no way we can do that
All errors are written to a global error_log on our system. The cPanel "Error Log" just searches this log for messages it knows are directed at you. However, 500 errors are usually split up across a couple lines, and the important lines don't have the identifying information. It's the fault of cPanel's search for not being able to pick those up, but the only way you can get access to them is to ask me to take a look.