My teacher has a Bell 4518 and an Excelsior Symphony. Both are fine accordions but the Bell is just fantastic as good as anything I’ve heard. If you ever run across a USA made Bell I’d be interested in your opinion. There are also some Scandalli Super VI that sound pretty awesome.I own several fine accordions including a Beltuna Spirit 4. I would agree with you that the Beltuna separates itself from most other accordions in every category.
I would also add that in my opinion, the finest bass systems with resonance and overall sound belong to Excelsior.
Again, this is my opinion only. Glad you had an enjoyable trip.
Dano