The amplitude of any celestial object at latitude ca 27^o S (i.e. Easter Island) may be approximately ascertained by using the curve for Thebes (ca 26^o N). With sun at summer solstice located at declination ca 23.5^o S the amplitude should also be ca 27^o S. So close to the equator (both latitude and declination), the difference between latitude and amplitude is very small.

Born in Europe I tend to think of north as straight up and that would mean 'mother' pointing northeast (about 45 degrees). In China I suppose they would think of straight up as due east (where the head of 'mother' is located), i.e. she would point southeast.

On Easter Island, presumably, she would also point southeast, i.e. towards summer solstice. She would rather, of course, have her arm more straight up, but that would be uncomfortable.