Inner 2 of 3 you actually need a longer BB rather than a shorter.
the middle space between the 2 chainrings is chainline center on a double.

you may need someone who can see 1st hand what you are talking about.

I ran a 2 of 3 double in the 80's , no issues .. 52-36
chainring guard just a bit bigger than the outside chainring..

so FD height was about the same as if I had the 52t on the outside
rather than the middle.