The part that I dislike the most is that this is the most finicky piece of software in all of the addons over the years
Which of course is wrong but, if you don't clearly explain what you are trying to do in detail, is impossible to tell you what you did wrong.
. It's like it never does what I want it to do.
It surely does, if you understand how it works.
Like now - I can't replace a jetway at KORD M16 for the life of me.
You don't say which scenery you are referring to. Assuming you mean the old FSDT KORD, it uses standard jetways so, there's no reason why it cannot be replaced on that particular parking. If you mean another scenery for KORD, as explained so many times on the forum, depending on the kind of jetways the scenery comes with, the replacement procedure is entirely different and, in some cases (static jetways not separated from the terminal mesh), not even possible.
In addition to that, I don't understand what this post has anything to do with jetways docking with AI, which is the thread subject.
If you need support for GSX, open a new thread in the support section (this is the backdoor section, which discusses new features), use a proper subject, and clearly describe your problem so, as usual, we can first check if you are doing something wrong and, if it was *really* something that need a fix on our side, we'll fix it.