I understand how you feel, as someone was previously assisted in the past regarding the same issue.
To provide you with some insight, if we assist you and our developers identify the issue, any compensations or retroactive fixes might not apply to you because we, as Game Masters, intervened.
We want to ensure that you receive the best support possible, but sometimes our involvement can affect the outcome. This is why it is very important and necessary that you and all other player submit your bug reports and report everything that might not be working as intended.
I fully understand how this may be a different outcome from what you were looking for, however I do want to assure you I would provide you with a workaround or alternative if any were available. I truly appreciate your patience and understanding.
Should you have any further matters for us, please do not hesitate opening another ticket, and we will assist without further ado.
The replies are just getting worse and worse.
I don’t even understand anymore.
Edit:
Well, after explaining my over-10-year-long journey to them and saying that from now on my only purpose in the game will be to log in, check mail for Guest List Page, and log off, all I got was:
Since you’ve already submitted a bug report and posted on the forums, you’re taking the right steps to bring this to the attention of our developers. They will review your report and investigate the issue further. I encourage you to keep an eye on the forums and patch notes for any updates regarding this matter.
I truly wish I could provide a more immediate solution, but please know that your feedback is invaluable, and it helps us improve the game for everyone. If you have any further questions or need assistance with anything else, please don’t hesitate to reach out. We’re here to support you and ensure you have the best experience possible in Azeroth.
Guess this is it. But I did alright… 44k+ achievement points, 900+ mounts, 800+ toys, 1000+ unique pets.
Nothing lasts forever, I suppose.
Thanks for trying to help. Take care, friends. 
One final edit for future reference:
Here’s the summary of my experience with the customer support:
- One GM told me that support depends on “specific circumstances” and individual factors.
- Another told me outright that GMs can’t grant those items at all.
- Then one said they don’t recommend trying to redo the entire achievement on another character.
- A forum blue post later told me that I should consider starting from scratch on another character.
The argument of a “policy change” only came up as a last resort, after those multiple conflicting explanations from different GMs.
I fully understand that item restoration policies may differ for items that are farmable versus those that are not, but in my case, I was told not to farm the item again. That creates a unique scenario where I’m not being allowed to re-earn the item nor receive support assistance, effectively locking me out with no path forward.
GG