Thanks, I'm glad you're enjoying it! I have a spreadsheet. It should really be a flowchart, but it's become something of a monster now, so transferring it over to a better system would take time I'd rather spend working on the game, ya'know?
For events, all of them are technically achievable, but not all of them are really intended to be achieved. There's a scene with Lani that requires max level cat person (or party planner), which means getting her to level 100... but I don't have high level monsters in the game yet. Similarly, Marla's hold-your-breath challenge doesn't end until over 5000 endurance points... there are other ways to finish it in planning and I never intended for anyone to grind that much, but many people have done so. The other hard ones are just not well-worded in the hints... People are having a hard time getting Lani's massage scenes because I simply failed to mention that she needs to be in your party for later versions to activate.