Thanks for sharing Nimiria, and taking time to post the pictures!
To confirm these gaps are completely harmless during sieges - as that is impassible terrain. However - from the visual point of view we did mess up here. Before these empty spaces would be filled up by large Cliff objects, so most of these empty spaces would have high cliffs. Couple of months ago we ran an update to remove thousands of small stone objects from all the maps to boost performance, but unfortunately we also removed these Cliff objects. This also made most of the homelands maps have small visual glitches.
We did plan to fix this, but had to hold off until the next major patch, as distributing this update would make for a large 200 MBs patch. However - it is planned later this November, so after that patch your homeland walls will look much better.