She gives you special text if you give her a Blue Moon Ice Cream?
I really hope this isn't the case. Tossing all of the candy and ice cream from your bag, leaving the Water Treatment Facility, and then grinding endlessly for a Blue Moon Ice Cream just to unlock a better story branch is quite possibly one of the least enjoyable things that I can think of doing in a video game.
This entire concept of "seemingly-trivial-yes-or-no-questions-throughout-the-story-actually-secretly-contribute-to-a-good-or-bad-ending" has a very feel-bad vibe to it. In my opinion, they have the serious potential to detract from one's enjoyment of the game.
If the player is aware of the alternate ending mechanic, then it puts pressure on them whenever they're presented with a choice. "Which of these choices is the 'correct' choice? I have no way of knowing until the game is completed in the distant future."
If they aren't aware, then the inevitable revelation will leave them thinking, "Oh god, have I been screwing up throughout my entire playthrough? I've been progressing through the game, yet I've still been doing things wrong that I can no longer change? How is that fair?"
That's how I'm feeling right now about which item I give to Titania, and it's how I feel about whether or not I should battle Taka. I'm no longer enjoying the experience as much as I should, because there's a constantly-looming question of "Am I doing things properly? If I make the wrong choice now, there's no fixing it later."