I very nearly didn't post this because I'm becoming more and more convinced that you're trolling everyone Bryan See. If you are, bravo for sticking with it this long. But on the off chance you're not, I'm going to be as straightforward as I can here.
I'm not a coder, and I have very little idea how FSOpen works at that level. But I have been screwing around with this engine for the better part of two decades, and based on that, I can all but guarantee that you are barking up the wrong tree expecting the coders to fix this for you. You may think you are helping by posting five year old threads from another forum about fixing a vaguely similar problem in a totally different application, but you're not. At best, you're wasting your time, at worst you're antagonising the people who you claim you want to help you by suggesting what I'm sure are, to them, relatively obvious fixes for a problem that doesn't actually exist.
The problem appears when Woutersmits tries to play your mod as a standalone, and nowhere else. That means there are two possible causes: Either you have a corrupted or missing asset that is causing the issue, or Woutersmits has improperly loaded your mod. One of those is the cause. If it works for you, then it's the second one. Simple as that.
Nobody else can fix this for you. You have to put in the work here if you want this solved. Talk to Woutersmits. Make sure that all the basics are done right. That you have the same versions, that he installed everything to the correct folders. Make sure that you didn't miss any files when you uploaded, and that he didn't miss any when he downloaded. Make sure he hasn't changed anything recently that might be causing the issue, like drivers or whatever. See if you can reproduce the issue on your end. If you can, great, you're narrowing it down. Then go through all your assets systematically. Revert to earlier versions until you find one that works. Go back to being FS2 dependent, see if that helps. Eventually, you will find the problem, but nobody will solve it for you if you can't find the source.
You have this huge, insanely ambitious project planned, and a frankly ridiculous concept that dozens of people are going to flock to help you realise it. That's not going to happen. If you want to put anything out, sometimes you have to be willing to put in the boring, time consuming work yourself. This is one such instance.