I think I found a better way than hex-editing to get rid of the bug where the Urgoth doesn't want to climb the ladder - I played around with the tower's GR2 file. Now there's no small hole on top of the tower but it's wide open so the Urgoth can fit through and get ordained favor. Am I allowed to upload my modded GR2 file somewhere and post a link to it, so players can finally play the Urgoth correctly without having to hex-edit every time they want to go up that tower?
edit: added a picture where my test urgoth has just gotten ordained favor. It's difficult to see because the shade was just casting a "stream of ruin" (I call it that because the Ring of Ruin casts the same spell), but in the top left corner you can clearly see the Urgoth icon.
edit again:
Fix for the Urgoth Bug - replacing the Ruins_TowerA.GR2 in the grn_model folder with this one will make it possible to climb up even if the player is an Urgoth. It also works on existing characters, even if their savegame is at a point where they are just climbing up. However, it also makes it easier for the shade to get the character, and it makes it a LOT harder to get down again after activating the altar. If you use this file, it will give a whole new meaning to the term "ordained favor", that much I promise you!