Absolutely nothing fucking happened. The concept was very intriguing and I'm not most readers were waiting for a love triangle but nothing ever happened.
Moto never said anything like that, in fact with their age and Chie's age, it's very probably that Takagi got pregnant right at the end of high school.
The author made their relationship into mother-son a lot more than pre-serialisation version. But even this version sometimes sneaks in some sensual stuff.
Well yeah, he was a normal Japanese man with black hair before, afterwards he turned into a young white girl with blonde hair and shark teeth, right now he turned into an adult male version of his isekaid form.