Buzzing on an acoustic will just sound bad over time. I would take it back, there might be a moderate adjustment they can make to the hight of the bridge that fixes the buzz, but makes it a bit easier than it used to be.
Give it time to cleanly finger chords and notes, i have been playing for about 20 years, and I still suck, but i am a lot better than i was even jsut 5 years ago. Hand strength will let you fret those notes more easily, and faster, you can also keep a light touch, it is about practice.
It is possible to dress the frets a bit in the areas where it is buzzing to keep the action where you have it. I would leave it up to a pro to reccomend, maybe Light or Muttley have a thought there. In general i would say that if the frets are even across the guitar, filing frets to avoid buzz so you can lower the strings because you haven't devloped techinique to fret the chords is not the way to go. Please don't read that as an insult, I have had and still have the same struggles. If however those three frets are a bit higher thant he others, it might make perfect sense to level them and kill the buzz.
One last thing, intonation for an acoustic is usually set for a specific gauge of string. If it is intonated properly now, and you change to a lighter string gauge you might not be intonated when you are done, without adjustment (moving the bridge basically). You might not be concerned about intonation around the 12th fret, but it is something to consider.
Good luck,
Daav