Athal's ability only affects Pilgrim's Cairn as if Cairn had a vision of 1, even if Cairn's vision has been increased by Constable. Oddly enough, this seems to be new as it did not used to happen.
You may ask how I noticed such an obscure thing. Well, it makes Cave's latest version of Renegade Timesap pretty much impossible to solve. Confirmed with game against the AI, ref 171762.

The trick is that Pilgrim's Cairn actually have vision 1 at the moment when Athal the Horrible ability triggers. It depends on order of creation things an in Cave Trolls puzzle it happens next way:
End of Round happens
- Pilgrim's Cairn created first, so it loose bonus vision, because Constable's ability says that building have bonus, so it works on it's own order, not at Constable's;
- Athal trigger it's own ability;
- Constable gives vision to nearest building (i.e. Pilgrim's Cairn).

P.S. Renegade Timesap can be solved - I can solve it and also there's at least two ways how to solve it (one way use not all cards).

Cave updated all his puzzles on 8-7. I solved Renegade TimeSap prior to the last update. The error was not occurring then. I defy you to solve it now. I apologize for the large amount of pictures, but I see no other way to show you what is happening.
End of Turn 1: Athal is just outside vision of Cairn. It should gain a health.
Turn 2: Cairn gained a health and it’s vision expanded to 3 due to 2 Constable’s being present. Cairn gains a health, but it sees Athal so it loses a health. I think this means it should stay at 2 health due to Athal.
Turns 3-5: I do nothing. The beasties keep chipping away at the Walled Outpost. The ones that see Athal slowly die. The Cairn, which also sees Athal, takes no damage.
Turn 6: Moved Athal out of range of Cairn.
Turn 7: Note that Cairn has lost no health at all. Why? It has been at 3 vision since round 2 and Athal has been at range 2 since end of round 1. To my reckoning, it should be at health 2. I move Athal into vision of Fortress.
Turn 8: Fortress has lost a health. It went from 9 to 8. Why did it lose health when Cairn did not?

Same thing, except at the beginning of turn 3 I move Athal to be adjacent to the Cairn. It does not increase in health from turn 3 to turn 4. This says to me Athal affects Cairn at a range 1 (it's base vision), but not a range 2 even though it has vision 3 from the Constables. Why? I do not understand. Can you explain it to me?

See my post above to see reason why Cairn doesn't loose health.

I still can solve that puzzle same way I did before - checked few minutes ago.

The previous way I solved the puzzle does not work. I can solve it still, that is not the primary point. My previous method depended on Athal and Cairn interacting the way I am insisting they did. The way these cards interacted has changed.
You can claim the current method is not a bug. Fine. It is an obscure action, unlikely to occur in actual game play. Not that big a deal, even in the limited world of this game. Please do not tell me I am imagining the previous manner of interaction. My solution to Renegade Timesap depended on it. I saw it work, and took delight in finally solving Cave Troll's most excellent puzzle.
Maybe the ultimate answer here is that in revising the puzzle, Cave Troll changed the order in which the figures were created.