From what it appears, many of these are complaints without merit to the FCC. Radio stations are protected to a certain grade of signal. Beyond that dividing line it's just space that can be filled by another station or a translator or just open. Thus, there is no interference because the protected grades of the signal do not overlap.
Do FM translators do better than the AM counterpart? Almost always. AM radio gets about 5-15% of radio listeners (the Northeast is closer to 5%). You can hit 1 million people on your AM station and we determine you have a .1 or 1,000 total listeners. Your FM translator hits 100,000 people and the same format you have about 2,000 listeners. Result: 10% of the reach but 20 times the listeners means double the audience of the AM.