auto perspective alignment seems to give better results in Lightroom. More realistic results, while Darktable often times completely warps “the space and time” of the image. In those situations one would like to manually add perspective lines like you can in Lightroom but in DT you can only enable or disable the lines created by the algo which is a lot more work than just manually adding 3 lines and you can never achieve the result you want, only what the algo gives you.
And while you are enabling or disabling those lines with a brush like tool, keep in mind you cannot change its size so you’ll be brushing a lot since the default brush size is pretty small, or you’ll brush over lines you wouldn’t want to since the brush size still isn’t so tiny tiny when you need to brush over the line that sits in the middle of a few other close ones.
You could achieve anything with sliders but let’s face it, you’ll never get the perfect result however much you tinker with them.