Phantom

Okay, then explain why Arwen goes from being extremely healthy in Book 1 (when Arwen gives him the relic), to nearly dying in Book 3.

Lulz. She doesn't give him a relic in the books that you clearly didn't read which is why you're in this situation in the first place.
Why doesn't she give it? Because it doesn't exist in the books.

Not to mention Galadriel had her own that she could have given Aragorn during the Fellowship's departure from Lothlorien (Book 1) - yet didn't because Aragorn had his own. If Galadriel KNEW it had no power, why keep it?

If Galadriel knew it had no power, why give it?
Epic logic!

Obviously SOMETHING kept the Elves in Middle Earth alive for so long,

They're immortal by their very nature. That's what keeps them alive for so long.

Read the Silmarillion. Or, you know, the actual LotR books.

However, this doesn't explain how Aran didn't affect anyone near him when that curse activated on him.

Seems to me you answered your own question.
Ellul, and everything in it, was tied to Mercedes' power.
So, when she was cursed, her kingdom was cursed.
Actually, it's stated specifically in Mercedes' quests that the curse's will wain as her power is restored.

Aran wasn't a ruler and didn't have such a magical link to his people.

Another inconsistency is how Afrien is apparently ALIVE and well in Evan's story, yet Freud isn't. Evan's story needs a revamp badly to explain that one (since the story factors that Mercedes doesn't exist at all, yet clearly she does, as referenced by how said scene was retconned in Mercedes' intro).

What "story" are you talking about?
Afrien was never killed in the past; Freud was.

And I also see no where where Mercedes should appear but doesn't.

Without explaining the inconsistencies via a revamp and second retcon to factor new lore into the equation, the previous heroes' stories have some giant gaping holes which make it hard to tell a story.

There is no need for any retcons. From what I see, everything is consistent, plot-wise.
The only inconsistency is that every new Hero has had a more fleshed-out story than the previous due to the way the story is being developed.

Also, adventurers need a story.

No.

Giving Adventurers a story would mean they would no longer be true to their names.
They aren't meant to have a predetermined story.
They aren't meant to have a destiny.
They're meant to be what we want them to be.

Then the question remains: What is Testonen's first name? If they're going with the "Letters of MAPLE" theory, then it's QUITE obvious that Kyrin's LAST name would be the same. Meaning Testonen is the surname, which means he HAS a first name. Question is though, what name would keep within the "Letters of MAPLE" theory?

I've actually suggested this theory before.
The only issue is it relies on Testonen being alive despite being reported dead.