There really is no good solution. It is what it is, especially for those who have to play in a wide range of climate conditions. I believe the best thing to do is when it happens, have a luthier dress the fret ends right then before the humidity rises and the wood swells back. If the wood swells beyond the fret ends, it isn't noticable anyway.
Or, anticipating such, the fret ends can be cut and dressed short to begin with, but this risks them being uneven, so I'd rather have the dressing later.
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