I think spyderarachnid is confidently wrong in this one. Hana is definitely omitting some information, but I think it is more likely she's playing things up rather than down. Curious what those "several hints" in the dialogue are supposed to be, and how many of them aren't just Hana's deliberate teasing or Tatsuki's own internal paranoid thoughts.
Regarding the lingerie photos, notice Hana only said she didn't have anything else to send at the time, she carefully worded things in a way that was both ambiguous and technically not a lie. Now why didn't she send the nude photo? I can think of 2 scenarios that keep it in line with the "wholesome" vibe of the game:
1) She's saving it to send in the future, she's not keeping it hidden forever she just wanted to save it for better use in a future teasing opportunity, probably for a play when she actually wears the lingerie while having sex with Yuma (would be funny if she gets suspicious of Tatsuki's lessened reaction to the second pic in the event he had already seen it before by snooping through her phone).
2) She lied about Yuma taking the pictures. Notice she wasn't the one who first said Yuma took the pictures, Tatsuki assumed it and then she went along saying "oh yeah he had to take the picture with his eyes closed that's why the picture looks so bad", what if the picture is bad because she took it by herself while keeping the phone propped up against some other object? She took both the one with her panties on and with her panties off, decided the one with the panties off was a little too much for the play of saying Yuma took them and so decided to only send the one where she kept her panties on.
The game's writing is cool because different people can see different things depending on what they are looking for, but dev has already confirmed this is a wholesome netorase game. I find it extremely unlikely that the game will ever confirm Hana was looking forward to "cheating" on Tatsuki this whole time and just playing him for a fool, much more likely is that Hana's pov will let the player "peep behind the curtain" and see how she went about putting this whole show for him. At most maybe the 2 different routes could be treated as "alternate realities", in the sense that the wholesome route could confirm all optimist and trusting thoughts, while the "darker" route could confirm all negative and suspicious thoughts (the game's universe is retroactively defined by the player's decisions).