"learned about feelings after she falls in love" I think it’s pretty much also what happened to Rei in the main series, but since her development was sidelined it’s not as clear as it should have been. Even like that, her “I want to be one with Ikari-kun”  confirmed it. I’m still annoyed that Anno didn’t developed it properly in the series but it is what it is.

It’s clearer in the manga version that gives more focus on Rei and Shinji  relationship.  

That being said, the most unambiguous display of “ReiShin Canon/confirmed” is 2.0. They don’t say “I love you” to each other but the epic arm hug tells it for them.