It might affect dispersion at very high frequencies and also cause VC alignment problems as previously mentioned
Here is a fix. place a dab of thick cyanoacrylate glue on the end of length of sowing thread. Swing the thread into the dome so the dab just contacts the dome at the center of the dent and sticks. Carefully drape the thread over the top of the loudspeaker without pulling it off the dome and leave it overnight. The next day gently pull on the thread until the dome pops out into (hopefully) it's original shape. Then carefully snip the thread and as much of the glue as you can take off the tweeter with fine angle cutters. Any glue remaining on the dome can be removed with acetone. This is how auto body guys pull dents. They weld rods to the sheet metal, pull the dent then grind the rods off. I would not try Bondo on the tweeter;-)
Here is a fix. place a dab of thick cyanoacrylate glue on the end of length of sowing thread. Swing the thread into the dome so the dab just contacts the dome at the center of the dent and sticks. Carefully drape the thread over the top of the loudspeaker without pulling it off the dome and leave it overnight. The next day gently pull on the thread until the dome pops out into (hopefully) it's original shape. Then carefully snip the thread and as much of the glue as you can take off the tweeter with fine angle cutters. Any glue remaining on the dome can be removed with acetone. This is how auto body guys pull dents. They weld rods to the sheet metal, pull the dent then grind the rods off. I would not try Bondo on the tweeter;-)