It is a pity that your currently newest scenery - released in 2017 - includes such a visual glitch, only to accommodate for an outdated prehistoric platform. I am hoping that you will at some point revisit this scenery and sort out this bug.
Even if it's a scenery released in 2017, it's design started more than 2 years earlier, when nobody even knew a 64 bit sim was in the works, so we couldn't afford to dump FSX back then. Then, in June 2017 P3D4 came out, and changed everything, but the scenery was almost finished by then.
I am also hoping that the upcoming KORD will not sacrifice anything quality wise in favour of FSX.
That's the main reason why we decided to stop supporting FSX: because we are fed up of not being able to do what we *can* do, just to support a 11-years old sim. KORD won't have a single bit of FSX technology in it.
However, the issue you are reported, will still be tricky to fix entirely, because even P3D4 cannot simulate objects below ground or bridges easily, not without causing all sort of trouble with other items, like AI. The main issue, which is the same reason why the sim still doesn't support sloped runways, is that AFCADs paths are not "3D" so, regardless how the scenery is modeled, the sim always assume the airport to be logically flat, if you take into account AI and ground vehicles too.