" Is modern smokeless .32 Short ammo safe for this gun? "

If the revolver is in good condition, the answer will be absolutely yes. Keep in mind that smokeless powder .32 S&W loads have been on the market since 1894, and many of the old top breaks have probably fired nothing but smokeless ammo. There seems to be some fear that smokeless loads are dangerous in some old guns, and indeed that may be true in a few cases. But the .32 S&W is not one of them.