Yes, it was typical that General Orders for awards were issued sometimes months after the action.The awards had to be approved up a chain of command before they were issued.
Also, GO's contain many names for many different awards (everything from the Medal of Honor to the Bronze Star). I'm taking a guess here, but I think they waited for names to pile up a bit, rather than issuing a GO for only a couple of soldiers.
I kinda expected that response from NARA.They don't have the resources to search through every GO for a reference to one soldier, and there's no master index for Bronze Star awards.
Another choice is to hire a professional genealogical researcher in the DC area, who will physically search every GO for the reference.Unfortunately, they typically charge $50-60 per hour plus expenses. Just do a google search for genealogy research if you're interested in this option.