Yay! 
Some points of interest are:
So summary of the things’s we’ve learned since last time:
Id trust them. We wouldn’t know anything without them.
The wording was “castle or church”.
If we’re talking about the Kemetic trio being stuck on the mundane side of the wall… Neuschwanstein is a castle on a mountain…
So this is what I’ve got but I feel like I’m leaving things out…anyone got things I’ve missed?
To the Searchers,
Since we last spoke, we reached out to the Cagliostro and Martin Rank. The Cagliostro is protected by her own magiq and we assumed she didn’t receive our message, and we’ve just received a response from Martin. It turns out that she did receive our message and was able to convey some information about our situation. From them, we’ve learned that the “veil” is a wall sectioning off part of the world. A wall with a closed door. She believes that if we can illuminate the door, she can find us and do…something. Can you tell us anything about shining a light that would illuminate this door?
We also got some news from Martin about some people he was keeping tabs on – Alison, Port, and Jeremy. They’ve left the place they were staying, and we were wondering if they’d found their way to you? One of them left drawings of mountains and castles and the message “Search for Magiq”. If they aren’t with you, can you see where they went?
Sincerely,
The Mountaineers
That sounds good to me. The only other thing I might add is how the door is deciding what can and can’t pass through.
Ooooh yes, that would be important 
Will add that in. Anyone else have ideas while I get a new draft ready?
Yeah, I’d tell them as much as we can. Every detail counts now.
Agreed. The more we can get through while we can, the better. Do we want to make any mention of what Lauren said to Marty about finding artifacts in the walls of the old loft, or do we reckon that was dream stuff leading to the clock?
That’s a good point, @Sorrel. She did say he needed to look for the artifacts built into the walls, artifacts with power, and we needed them to see through the cracks.
So an artifact inside the wall? The Aliquary?
I don’t know. I remember The Cagliostro had artifacts from The Book of The Wild built into the construction of his loft, per Lauren’s emails, and when Martin went to the loft after the performance, they’d all been stripped out. Might have just been metaphorical dream stuff, or maybe she was cluing him into… something.
What if the wall is the veil and not a physical wall? I don’t know if you can use magiq to fold things out of our space or not, but hiding the items in a spell meant to hide and keep things out seems like a good countermeasure to me.
Quick edit: I mean the wall that Lauren mentioned in particular
Yeah, I think the wall Lauren mentions is the veil that the Searchers sensed. Lauren just put a more concrete (no pun intended) spin on it.
I guess. I figured lauren would have taken them all. So i doubt she meant for him to physically go back and search the loft.
Hmmm. Why hint at anything when she just went on to directly talk to him later? Dreaming was a more private way to tell him something important? Maybe theres something to it.
I always figured it was the Silver who took the artifacts. But Lauren… 
She said in a recording she knew they were there before she became cags. I figured that would be her first stop…and to get her toothbrush of course.
Maybe the previous cags put them there to act like an incubator of sorts for her. I’ve always wondered if they were for more than just warding.
Artifacts in a wall… I have a few theories on this.
Also, yes, @Saberlane, giant napping sloth is wierd, but courier weirdness is almost to be expected at this point. What’s more concerning is that you wouldn’t answer Marty’s calls, even before the veil cut you off. I don’t mean to sound scolding, but he’s an important contact for AGP and the Mountaineers.
I have phone fear.
Should the artifacts in the walls be added to the letter then? I sort of thought that was a for-Marty thing, but I could add in the bit about the dream in case it means anything to the searchers?