I stayed at Lembeh resort in early December of 2019.
The dive shop - a little below mediocre. Message privately for details.
But the resort - world class.
Yes, they have rooms on ground level. Right behind the main building.
I stayed there before getting upgraded to one of the newer villas on the cliff.
The thing is I don't remember seeing an elevator in the main building.
The main dining area, bar, and lounge is on the first level. Not too many steps to go up but you do need to go up to access the buffet.
I'm more than certain Turk and his team will find a way to accommodate you though.
You could probably financially reward a few friendly staff to carry you up - but I don't know how you'd feel about that lol
this is the ground level accommodation building