Yeah it's brutal. I've been using Godot professionally for years. I have effectively mastered the layout system but it was annoying to learn. It tries to be like Unity's system but they made a few mistakes with Pivot, Grow Direction and Size Flags imo.
I made a tool to position nodes in a way modelled after Cocos2D, with a position, pivot and anchor point.
I've made a series of small tools to help me lay stuff out.
One really good thing about Godot Ui is the "StyleBox" which simply allows coders to make rounded rectangles, which are so frequently used in UI it's nice to not need an artist to make a .png