Honestly, the whole search for a spill-proof pen is a trap. You're focusing on the wrong fix. The real problem is using a planner that can't handle life happening. A coffee spill is just Tuesday. What about rain, a leaky water bottle, or just the humidity in July? No pen ink stands a chance against a soaked page. The trust should be in the paper itself. I moved to a notebook with waterproof paper years ago after a similar disaster. Now I can use any pen I want, even those cheap ones, and a spill just beads up. I wipe it off and keep writing.