Yes, it made perfect sense that Antonin would come running straight to Cornwall. The largest reason why she refused to stay any length of time in his house after Augustus took her out of the Leaky Cauldron was because she had the suspicion that her husband would eventually make his way there to see for himself that she was hidden. Likely he'd been there over a dozen times since she disappeared. He probably had even been to France more than once to make sure the Ambassador wasn't keeping his wife tucked away in a little cottage in the French countryside. Where Augustus was concerned, Antonin would never be able to think clearly and without the raging jealousy that had always been a part of his personality. Because of his known feelings, she couldn't ignore the worry in the back of her mind that she should've seen him approach Augustus" house at least once when she was hidden in the grove. She knew she could've been asleep for one, possibly two visits. All three? Highly unlikely. Something was off.