yes you can do it, we have more than a few hugelkultur terraces. i do recommend that they have some height to them, even if it is a couple inches. this makes the pathway act as a swale in heady downpours. which the hugel beds gladly soak up and hold or distribute slowly
underground.
you also have to take into account that if your hugel terraces are 12" when you start. when the
wood decomposes it will drop 6-12" or more leveling out. if you went level at first it would still sink and a terrace with a downward slope does very little good.
i also find it helps to have some space between the terraces on the slope if you do hugelkulture beds. this is where most of the excess
water is released and where plants thrive. connecting terrace to terrace does work though.