There's basically only one result you can get from an appeal which is "we have reviewed your account and we will not be lifting the suspension at this time."

The appeals process exists to fill a checkbox that says there must be an appeals process, not to actually unban anyone.

I have seen multiple people have their shadowbans reversed after I recognized it had occurred and alerted them.

I appealed a warning I was given for quoting a Simpsons episode (promoting violence, Reddit-wide and not from a sub) and was my appeal was granted.

As I said, the appeal was granted, or at least that's the message I got in reply.

However everything remained in the nether-realm and the appeals page claimed that my account was normal, and that therefore couldn't be used

No response from any support ticket either. They still advertised me IPO opportunities though...

That's strange. I've never seen that set of circumstances. Pop me an email on my profile and I can try to put you in touch with someone who might be able to help.