Oh. What are the scenes anyways? Are they part of the beach scene or the halloween stuff?
One of the scenes is after the beach event chain, but before the Christmas event chain. When Rin is still recovering from Chika's rejection she decides to go out with Futaba to clear her head. If you didn't break your promise to her you go along with them, and this is Rin's first meeting with Otoha, as well as Sensei's first time meeting Otoha. If you didn't get this event Rin later introduces Otoha to Sensei and mentions they met off-screen.
The other missable scene is at the very end of the current content and would be a spoiler for you, so I won't talk about it. You can also still get this one if you enter that cheat code.
Not betraying Rin also alters another event after the Christmas event chain. In this one you're hanging out with Rin in her room when she gets a text message from Otoha. If you betrayed Rin she focuses on her phone and the event ends there.
If you didn't she instead
drops her phone and kisses Sensei. This one should also still be possible with the cheat code.