It looks like the roof of the second level is bigger than the floor of the first, is that right?
You made a good assumption ! The inner circumferences and thus diameteres of both levels are exactly the same. The second level is straight under the first.
But don't worry about the light not reaching it, from the azure sun. It is located like 10km above the point
B and first level don't cover its light from reaching second level.
Also about points
G and
M, they are there only for calculation purposes, as they form cones, which part are the levels. So lines coming from it, don't really form any material object.
Material edges of the Yliakum are |ADHK| and on the other side |CFJL|.
This should help a bit.
And yeah, books need illustrations, but what i did would still need to be processed through some filters and stuff, so that it would look like made by eg. pencil