Why would I believe the word of some Biden appointee?

Again, these weren't Biden appointees. They were the Trump appointees. This was the report that the Trump appointees issued themselves explaining their vote. Not the Biden appointees.

He's committed several felonies, the easiest of which is falsifying his federal gun permit paperwork.

When's his trial start?

A few months after a prosecutor assembles sufficient evidence that he has committed a crime.

I assume you're referring to this incident:

insideedition.com - FBI believes they have evidence that hunter biden lied on application to purchase a gun in

...which very well may result in criminal charges against Biden. But unlike the Trump case, which is based largely on documents that the authorities already have, the Biden case requires some extraneous proof.

In order to prosecute that case, they have to prove two things. First, that Biden was addicted to drugs at the time he filled out the form. And second, that Biden himself believed that he was addicted to drugs. That's not an easy case to assemble, because the obvious defense against that (he was addicted to drugs before, but he genuinely thought at the time he filled out that form that he had kicked the habit) requires some fairly good evidence about his drug use in 2018. Which may not be very easy to assemble today. You probably want to wait until you've got a good idea about the last time he used illegal drugs prior to submitting that form - whether it was the week before or the month before or the year before or what have you.

But that said, if Hunter Biden lied on his gun application form - go ahead and prosecute him, if that's something that is a criminal offense!