Just one more data point, and not directly to a Form-4 application: A "Youthful display of patriotic enthusiasm" at the wrong place and time resulted in an arrest for discharging a firearm and illegal posession of a firearm when I was 18. The charges were soon dismissed, and all was well, for some 35 years. In that time I received security clearances, two different CCW permits, multiple pistol purchase permits (in NJ where they are required), and passed many NICS checks.
Then... I applied for a FFL.
The BATFE sent back my application "pending clarification" because they saw the arrest. The letter I recieved basically said "we see the arrest, we do not see a conviction, but neither do we see a dismissal or any other information". They informed me that I needed to provide a letter from the judicating authority stating the end result (dismissal, in my case). This took a LOT of time and trouble, lost records from 35 years ago. In the end they were found and the BATFE was happy. The final act on my part was to end the issue once and for all with an expungement of the arrest, which took 3 months and cost me $600.
The point is that the BATFE does look further than the basics in the NICS check. I passed those free and clear for years, but it was a hangup for the FFL. I can not say if it would have hung up a Form 4 (I never tried to get one thru before I had my record cleared) so I have no clue if this information is germane to your case.
I would apply and if it is kicked back, get the documentation to support your situation, submit it, and go on with life.
In my case I learned not to shoot a 12 guage in my backyard to celebrate the 4th of July.....