Feature Config:

"I would be super-nice if there were a way to automatically align a point vertically or horizontally with adjacent points (e.g., holding down a modified while dragging or something like that.)"

Option 1: Snap to nearest point / vertical / horizontal (when within 5? x? pixels? mm?)
Option 2: Snap to grid (with tolerance: 5? mm?)
Option 3: Manual Edit via point table