No, I think I'm interpreting the arguments properly, I just find them completely unsupported.
Even if Mina is Ian's girlfriend, she doesn't OWE it to Ian to disclose her bucket list. They're her kinks. She's completely within her rights to hide them from anyone she thinks wouldn't treat them appropriately - and as
True_Degenerate illustrated, Ian has *deliberately* abused her trust and belittled her sensibilities pretty much from the get go.
Moreover, you imply Mina's innocence is disingenuous and I just don't agree. Her bubbly, innocent persona is an affectation, but it is not false. That's the person Mina wants to be, and thus it's how she tries to act. Mina doesn't see herself as a nymphomaniac so she hides that aspect of herself; the dichotomy between her preferred self-image and her overactive libido is a big part of why she's so reluctant to vocalize her fantasies.
Lastly, the idea that Mina will disclose truths to Hana she won't admit to Ian is flat out preposterous.
Ian is sitting right next to them during the game! The fact that only Hana was respectful enough to answer Mina's questions earnestly and wise enough to recognize the pattern in Mina's questions ought to make it crystal clear why Ian never learned about the list. Yet some people refuse to believe their lying eyes and insist Mina *must* have intentionally misled Ian.
It's a real headscratcher to me.