Yes, it is wrong to lie.
It's even more wrong to tell somebody is lying, when it's not the case. We might disagree on this, but NOT on inappropriate usage of the term. I never called YOU "a liar", even if I'm fully convinced (just like you are), you are wrong in almost everything you say. Saying somebody is wrong is not offensive, calling somebody a liar is, because saying somebody is wrong means accepting HE is honestly convinced to be in the right, I'm sure you are and I accept it, even if I disagree. Calling somebody a liar is offensive, because it implies malice and willingness to deceive, and that is NOT acceptable.
I haven't opened 2020 for 3 months, and haven't used Seated Passengers in 2020 on the MD80 for 10 months
Again, completely irrelevant. You wrongly accusing me of not taking this seriously back then, and while you might had had some kind of point, because then I said I only tested with default liveries, but your wrong accusation sounds even more wrong today, when I tested:
- the livery you said it "never worked" in 2020
- the livery you said it doesn't work now, in 2024.
In any case, I made ANOTHER test and guess what, it was as I suspected: it's the casing issue. I manually changed all involved files to match precisely the actual file/folders in disk, and by doing that, MSFS 2020 opens the airplane directly at the first try, without even having to enter the Hangar before. 2024 worked straight away, so maybe this is exactly something they might have fixed, because I can imagine something must have happened in other cases: it's very easy for any developer to miss a small detail like that, on Windows, shouldn't even matter, so perhaps there might have been some obscure bug report airplanes or liveries not loading, so they made the loading process more robust in 2024 SU3. We can only rejoice about that.
I'll try to investigate further to understand what is exactly the part that is case-sensitive: it might be the model.cfg or the exterior.xml, or both, and it might be just the path portion, or just the filename, or both and if it's found, we might come up with a fix.