Condor Fratello triple wrong length BB

My Condor Fratello campag triple has never shifted properly.  In particular, the ability to shift into the inner ring depends on the position of the rear derailleur, because part of the front derailleur (FD) makes contact with the seat tube, and therefore can't go in far enough to push the chain off the middle ring properly, but it also overshifts on the big ring.

It has a Centaur chainset from 2007, Veloce triple front derailleur also from 2007, and Veloce square taper bottom bracket (BB).

I needed to service the BB because it was getting lumpy and on extracting it discovered it had a 111mm spindle....but the Ribble site said I should use 115.5m, which was confusing, so I did a bit of digging. The advice here at the top of p35 says that for an oversized seat tube a BB of 115.5mm is needed.

The Fratello's seat tube diameter is 31.8mm so it should have the 115.5mm spindle.

To cut what is already a not very interesting story short, I have replaced the BB with a Centaur English 115.5mm and it shifts perfectly, which suggests that the whole geometry of FD is adversely affected by using the wrong sized BB.

I can see that it would be more 'cool' to have the shorter BB and better chainline, but it is at the expense of a bike that actually works properly.   Has anyone else experienced this with their Condor Fratello (Fratelli?)?  Or perhaps I am the last person riding a Fratello with a square taper BB?