After finally finishing the furniture of our newly built Dining Hall, I've called my family for our first feast. If you look at the picture, you'd think it was a success, however...

...the family farmer was trying to sit down for like 5 minutes. She was supposed to be next to me (I'm on the end of the table) however, since she couldn't sit there, we changed her spot.
I tried to show her how to sit there many times, but it seemed impossible for her. At first I thought that maybe she was coming from the wrong direction, or something like that... But then I went to her computer (we're in the same room IRL) and couldn't sit down either. I actually did, to be honest, but only after a lot of effort.
Something seemed wrong.
After some experimentation and guesses, here's what I (apparently) found: The farmer's hat gets in the way. Its collision box makes it harder to sit than other hats. Further experimentation with buckets and other pieces of 'big' equipment have shown that some interactions are complicated because of equipment collision. I understand some of them (it can be arguably complicated to traverse between tight cupboards with a scythe) but being unable to sit down on a chair because of a hat is simply stupid.

Fun, but stupid

Anyway, more experimentation under different conditions/character models (after all she's a female character, not sure if it happens to the male model as well) would be required to make sure if it's an issue that needs fixing. But here are some helpful notes:
1. This seems to only occur with hand-equipped items and hats. Couldn't see any difference when dealing with other pieces of equipment.
2. This also affected her mobility. Without any hats or gear, we could squeeze her through a diagonal cave wall after a lot of clicking! (also, moving the camera (rotating) so walls 'disappear' in caves seems to affect collision too... This has potential to be exploitable)
3. The chair and table placement on our dining hall is slightly different from the default game grid (using ctrl). The furniture is more tightly placed than by default. This could have some influence but we forgot to test on default spaced chairs & tables.
Hope any of the info is useful

- DaniAngione