I'm convinced that the "Maker," if there is one, is just a very powerful Fade spirit created from and/or fueled by millions of idiots' faith. (Much like how Nightmare is a personification of and fueled by mortals' fears.) After all, spirits are created when an idea or emotion gains enough force, then are shaped by the emotions and expectations of mortals. I'll also be convinced Andraste was just a very powerful mage and the "Maker" that gave her visions was just a very powerful spirit that gave her advice and/or went into her (like Wynne and Faith, or Anders and Justice) until proven others.
The Maker isn't in the Fade. Andrastianism is deist. Not theist. i.e. Their god doesn't care. He left.
Speaking of which, that's the silly thing about this game's premise. This was established lore before.. there's no reason why so many Chantry people would believe the main character was saved by Andraste. Only people like Leliana were like this in the setting before. It made her odd. Even Wynne criticized her. Now suddenly everyone in Haven is a theist and instantly duped by whatever character we can dream up.
True, but then that's not even the worst ret-con the devs have come up with. Wasn't Haven this deserted town too small for any map, filled with fanatical cultists who'd gone mad from centuries of isolation and started worshiping dragons? Now in DAI suddenly we hear of this Orlesian noble who owns the land? And discussion implies that Haven has been this thriving social/holy hubbub for years; not even a hint that a decade ago the town was filled with eerily quiet horror genre extras who kept muttering, "We don't question tradition" over and over.
Anyway, the Chantry preaches that they can get the Maker to care and come back if they can "spread the Chant of Light to the four corners of the earth." In other words, suck up to Him until He relents and comes back.
DAI also implies that people's religious zealousness spikes when they're afraid, and suddenly start thinking their god is loving and merciful and looking out for them because it gives them the comfort they need to cope. That is, thinking that a powerful deity is looking out for them is more comforting than, "The deity left, and won't come back until a few more centuries of sucking up." Mother Giselle also seems to be the exception to her sisters in that she also preaches love and benevolence while the rest of the clerics preach dogma and tradition (much like how Leliana was), so it's not too bad of a retcon...
Personally, I think Origins proved the existence of the Maker, and that the story of him and Andraste were historical fact.
But this was too much for BioWare. They needed to make it more ambiguous so that the Maker's existence would be something that people would question. So they had Corypheus suggest that the Golden City was black when they found it, which Corypheus then admitted was false at the end of Inquisition. But now they have the stories with the evanuris and the titans and how that fits into the Chantry account.
That's all this is, I think. BioWare just wants to make the Maker less of a fact in the series. So they injected doubt. The Gauntlet can now be explained as a titan residing under the temple, or lyrium running all through it, or whatever. Or maybe this was the titan Mythal slayed, and then the Temple of Andraste was built over it. The story about the Veil is also now in doubt. Solas claims he created it. The Chantry claims the Maker created it. Both can't be right. I think Solas is mistaken, as usual.
No, there's been room for doubt from the beginning.
DAO mentions that Andraste was a historical person, but whether or not the Maker was real or her claims to divinity were true were constantly brought into question. Duncan starts the opening narration with "The Chantry teaches us..." which implies that the Chantry might not be right. Pretty much every conversation between Leliana and Morrigan questioned the Maker's existence and the Chantry's version of what made the world. Bring Oghren into the Gauntlet and he comments that there's an unusually high and pure concentration of lyrium ore in the place, and around Andraste's Ashes, which could explain all the magic and mumbo-jumbo. You can give Wynne a book as a gift, which basically offers mundane alternative explanations to Andraste's supposed divinity.
And, given what we know about spirits now, they could have come to act as the spirits of the past rather than the spirits themselves. Certainly, if you play a Dalish Warden and go to the Gaunlet, the "spirit of Tamlen" is quickly proven to be a bald-faced lie, since you encounter him out there as a ghoul whose mind has been rotted away by the taint, so there's no way his spirit could really be at that temple. Speaking of the Dalish, if you bring Leliana to the Dalish camp she'll comment that the Dalish's creation stories sound a lot like the Chantry's (I think especially the "Fen'Harel imprisoned our gods" sounding like "The Maker imprisoned the Old Gods," though I can't remember), then wonders if they're talking about the same supernatural event / their "elven gods" are just different faces for the Maker.
So, yeah. There's been room for doubt from the beginning, and the devs have just been expanding on the history, events, and world outside the Chantry's teachings every game since.
Also, given that the Chantry are a bunch of willfully ignorant, self-propagating history revisionists (I mean, since DAO we've known that they slashed Shartan out of the Chant of Light just because they stopped liking elves, and constantly omit elven and mage heroes from the history books when they don't change them into muggles and humans outright, like in the case of Ameridan), I'll take the word of an ancient elf who was actually there and claims to have created the Veil over them.