If there are no grooves caused by the strings then a fret crowning can be done safely. The actual "crown", or top of the fret arc should not be affected significantly if the crowning is done with care.
If you feel that you have the confidence and skill to try this here's what you need to do:
First off, I'm assuming from your comment about there being no buzzing that you don't need a fret leveling before you crown the frets. If the frets do need leveling, there's another procedure you'd need to do before going to crowning. Here's the crowning procedure:
Step 1, tape off the fretboard to protect it leaving only the frets exposed. Use the blue painters tape for this as it will not damage the fretboard. This will take some time to do as it is a slow process. OR, you could buy some of the SS fretboard protectors that the fret protrudes from, while protecting the fretboard.
Step 2, Mark the crown of each fret with a black magic marker. You don't need to slather it on, only so much so that the crown is completely marked.
Step 3, Run the crowning file slowly, evenly, and lightly over the fret following to radius of the fret. Resist the temptation to put too much pressure on the file, a little pressure goes a long way.
Step 4, With each pass of the file stop and check the fret. There should be just a faint black line left top dead center of the fret when the crown is right. From there you just need to polish the frets and you should be good to go.
