I need to go back and look in the book to verify, but my recollection is that every time Spensa mentions the delver maze reminding her of something, she then experiences something that seems to be a mental connection to a delver. So the similarities she notices are actually the delver mirroring her own memories back to her (possibly in an attempt to understand her.)
the one instance that was separate was when she first entered the training maze, and noticed that it was very similar to the falling structure she flew through on Detritus - but that seems to be an indication that the humans had a separate training maze located there in the past, not any comment about Detritus itself.