I don’t think the onus should be on you to find a solution by yourself. You seem to be a tech savvy individual, but not everyone is. A lot of people wouldn’t have the first clue how to troubleshoot something like this. I also think that while a reasonable amount of time should be spent trying to resolve the issue, expecting hours of the customer’s participation in troubleshooting is far too much.
It’s hard to know where to draw the line, but I definitely think that if the product creates giant buildings that make it impossible to land somewhere, that counts. If it’s something that inhibits your ability to operate normally in the sim, that counts. Cosmetic issues are where it gets a lot more difficult. And all of these scenarios come down to the developer’s willingness to work with you and resolve the issue, too.
Ultimately, though, I think all scenarios like this ought to give the benefit of the doubt to the consumer. Especially if those 500 addons were purchased from the place you’re trying to get the refund from.
Regarding finding a solution to your problem, I reported a bug to Zendesk many years ago. I did an enormous amount of research and presented my findings to them. They dismissed it all; I’m not even sure they looked at it. And that was the end of that. I think Zendesk is a great place for reporting bugs, but my one experience asking for help there left a very sour taste in my mouth.
(By the way, it’s hard to imagine how giant buildings from Taiwan ended up in the Bahamas, unless another developer used their 3D assets, which would be really bad. But I’m sure you tested without addons and ruled that out. This problem reminds me of the giant buildings and runway distance remaining signs at MYNN many years ago.)