I totally understand the feeling about switching to manual mode, but it will help to tell you what’s going on. If you switch to manual and the wobble goes away you know you’re dealing with a tuning issue. If the wobble continues or get’s worse then it’s an aerodynamic or C of G issue and you should land and and fix that right away. You don’t need to stay in manual for long, you’ll know the answer pretty quick. The old rule for RC flyers was “start 3 mistakes high”. Give yourself lots of room, and don’t be afraid to switch it back to FBWA.
I do think your plane is on the heavy side. I noticed the throttle is over 65% for much of the tuning. It may help to reduce the weight if you can.
Verify the C of G. I don’t know the Dart-250, but Andrew Newton or Painless360 have a bunch of videos about them. What do they set the C of G at? Many manufactures will set the C of G a little too far forward to be safe.
I’m starting to form the opinion that ArduPlane sets the D term too high for wings. I noticed there is D term pitch oscillation in your logs. If you get the auto tune to a more satisfying place it might not hurt to reduce the D term by ⅓ to ½ depending on how much it’s oscillating. Also make sure you tune it while it’s glassy calm wind. Especially on a smaller plane like the dart if there’s any wind acting on it while it’s tuning that could mess things up.