Even though Tsukiko can't express herself, her body language makes up for it in tenfold. Her twitching her hair, the way her hair gets all frizzled whenever she becomes excited, her putting on his shirt because she couldn't find an apron (which I'm sure is because she actually played one of those eroge she found in his room. I'm even willing to bet she was naked underneath), all those are signs that she's fallen for him really, really hard, more so than Azusa.
As for Azusa, I can't really see him falling for her. He likes her and thinks she's cute, but his feelings for Tsukiko were far more clear and precise (partially due to him lacking any sense of shame), and I'm sure he'll eventually grow to love her (though it might not happen in the anime).
Last bit showed you that you should be careful what you wish for, especially in the premise of a wish-granting catgod statue.