Seems a good question to me Milandro.
I think i would hesitate to say that such patterns in the wood are on a "equal" footing with pamor patterns in terms of significance and importance. The blade is always central to any keris regarding such things. But certain wood patterns are indeed highly prized and do hold a certain protective status.
Here is an example from my collection that displays what is known as "Dwi Roh" motif on the gandar of the sheath. This means "Two Spirit" and refers to the two ghostly faces that can be interpreted in the timoho wood of the gandar. This is a rare motif that is considered to be a protective device. In this case this motif was considered important enough to preserve and was fitted to a newer top sheath (gambar) of kayu jati gembol (burl teak).
I am not sure how the vertical Adeg lines of your gandar should be interpreted, but probably not in the same way as when we see such a pattern as pamor in a keris. We tend to see the horizontal lines that appear on your gambar more often. But it is probably fair to assume that they are deemed as protect devices in some way or another.