I am late to the party, the question was already answered but since the documentation is a bit unclear I elaborated a bit more on my blog, especially because the Palette Offset works differently on 8bpp Sprites.
Color 0 is again transparent, so binary value of %0000 0000 will simply show the color of the layer below (if there is one)
Colors 1-15 will be affected by Palette Offset in Map data in the same way as in above example for 4bpp mode which makes sense because they only use 4 lower bits anyway and are simply complemented by top 4 bits from the offset. If Offset is 0 then Palette is unchanged.
Colors 16-255 are not affected by the Palette Offset and are taken directly from the palette. Note that this is different from the behavior for the 8bpp sprites.
DusanStrakl's post in scrolling in bitmap mode was marked as the answer