Oh man, my issues with Hidden Shrine, where to begin...
*A lot of encounters are vastly underpowered- this is a conversion of a 1st Edition adventure, and it shows: the traps are super-deadly, but a lot of the actual fights are barely a speed bump for Tier 2 adventurers. The only advice they give (and not even in the adventure itself, but in a "Hooks for the Hidden Shrine" article) is to "add one or two monsters". Gee thanks.
Mitigated by the inability to rest safely. When coupled with the fact that the PCs might not even realize that it's not safe to rest - as in, not try to conserve their resources, this is actually kinda nasty.
*Trapped in the Shrine: you can't get out. No going to town for you. Didn't buy potions or antitoxin? Oh darn.
Heavens forfend the poor widdle PCs should be put under pressure.
*Room 1: not that any of these enemies are challenging, but they only appear if the party decides to pick up little figurines and set them on the floor. My group just pocketed them all, lol.
*Room 8: oh no, don't touch the walls, you'll take acid damage! Except...nobody has any reason to touch the walls? Ooh, fake green slime! Someone might have to waste a spell on...oh yeah, this is an edition with at-will magic attacks.
Not every encounter needs to be serious challenge. Part of the fun of an adventure like this is just exploring and prodding things to see what happens.
Room 5: so you need 48 Strength to move a limestone block that deals 1 acid damage per turn you touch it, and it takes 10 rounds to move it. My party was really close to saying "screw this", lol. Also, science in D&D!
*The Battleaxe. No name. Powerful. Cursed. Unique rarity. Neat for a home game, trouble in AL. Also, why is there an option to "break" it's most interesting power? One of my Rogues removed the scroll thinking it was a map, message, clue, or just a spell scroll. Which is a reasonable interpretation...oops, he broke it. Which is sad because the Passwall might have gotten them out of the Shrine...
The real question you should be asking yourself is "why are the PCs pushing on the block in the first place?" Of course, a little application of critical thought should yield ways to push it without taking damage. The axe is powerful but almost impossible to find and comes with a hidden caveat. I like it, myself.
*Sleep Gas: What. Just...what. So ok, every round you have to make a DC 10 save. Fine. If you fail, you are poisoned, and fall asleep, ok, fine. For 5000 years! Which is admittedly hilarious, but the weirdness starts when the adventure says how you can be cured.
"If magic is used to cure the poisoned condition, the recipient is immune to the poison for one hour". My reading of this was that poison cures suspend the effects of the sleep poison for one hour. Several of my players immediately fired off "rules-argument.exe". Their way of thinking was that removing the condition just works, and ALSO makes you immune for an hour as a side benefit. My evidence to support my ruling was the next bit:
*A casting of Dispel Magic USING A SPELL SLOT OF 7TH LEVEL OR HIGHER can also end the effect. So many problems with this statement. I mean, first of all, none of the party members should have access to such a spell. This hearkens back to old D&D, where many "magical effects" in dungeons were randomly cast at super high level, to prevent players from doing anything about it. So poison removal grants "immunity for 1 hour", Dispel Magic "ends the effect". It's also conceivable that the Dispel is intended to get rid of all the sleep gas and anyone affected by it, but the text is very unclear.
No. This one's pretty simple - there are various spells and effects which can remove the "poisoned" condition without neutralizing the poison. Lesser Restoration for example. Then there are effects that can neutralize poisons - like Protection from Poison, or the Paladin's Lay on Hands ability. Oh the horrors, an adversity the PCs might not be able to cure immediately.
*The Glyph of Warding: by the rules, can be triggered by, heh, reading it. Which you kind of need to do, and really, how does detect such a trap? More of a problem with the spell...oh and what a spell. Save DC 17- by the rules, this Glyph was cast by a very high level caster. And even then, it cheats, because it hits every person in the tomb with Bestow Curse. And then...the adventure has the nerve to not say what effect the curse has other than a vague "every cursed violator receives a visit from Tloques or some other agent of Zotzilaha seeking retribution" 4d10 days later. Unless THAT'S the curse?
My reading is that that IS the curse.
*Room 9: this one was hilarious. After making the check to realize that climbing up the statue would make it tip over, my Rogue asks "so how do we get the sword?". My reply "Well, that's just the easiest way to climb up. Nothing stops you from climbing the wall the regular way". Legacy of an edition where only Thieves could Climb anything, and with a set percentage to succeed based on your level.
...except that whether PCs can climb random walls without an Athletics check is entirely up to the DM. I don't know many people IRL who can climb bare masonry without specialized training, equipment, and/or exercise regimes, myself.
*Room 11: more slippery surfaces that don't really matter. A solo enemy who goes on at length about how badass he is, then pleas for mercy. LOL. Then...a swarm of rats. Except it's a swarm of giant rats...who are diseased (yeah this was mentioned by the OP, but it bears repeating. What were they thinking when they wrote this?).
No, it's a normal swarm of rats with the disease ability possessed by the diseased giant rat variant. Since the disease prevents nonmagical healing from even short rests, this is actually a potential threat. (Once in a blue moon if the swarm hits and the PC fails a lowly DC:10 con save; and if the PCs don't realize they've been diseased and don't have a ready cure).
*Room 20: a. single. wight. Come on, that's not an encounter at this point. Also, now I can gripe about the Amulet of Protection. So there's a few of these in the adventure, which basically say "nope, Turn Undead don't work on this guy". Again, this is a legacy of the olden days, when you had to have a Cleric, and the only real anti-undead power anyone had was Turning. Now of course, you don't need a Cleric, and they have more interesting things to do with Channel Divinity, so the only time they might try to Turn is when facing a room of undead...like, say, 15 zombies. Not for a lowly Wight.
Wights are pretty disappointing in 5e. They work...almost sorta well if they try hit and run tactics to drain a bit of max hp before fleeing, resting, ambushing, and running away again.
*Room 28: a. single. gas spore. Well, the purpose of the spore is obvious, make silly players go "oh





, a BEHOLDER! Kill it, kill it!". Then it explodes, some damage is dealt, everyone laughs. I could add more spores, but since it's intended to represent the sun (which last I checked, we only have one of), doesn't make much sense. So this isn't properly an encounter at all, and the xp is negligible. I mean, I guess I could have the explosion alert nearby monsters and add a random encounter. Yeah, let's do that.
And then one or more PCs don't realize that they've been infected and perish horribly.
*Room 32: opening a door unleashes a trap! It's 5 heavy crossbows, rigged to open fire...wait. Should the makers of the Shrine have crossbow technology? Earlier we found a "sword" made out of laminated wood and obsidian...in fact, how long has the Shrine been sealed? Who's been repairing these things, should they even work at all?
There are and have actually been a fair number of primitive cultures that made use of crossbows. We're not talking crossbows with complex mechanical gears like in post-medieval Europe, but still effective....trap maintenance is a common dungeon problem. Next you'll be wanting to know why the sleeping martial artists didn't perish long ago from bed sores, or how the zombies can break the laws of thermodynamics. Although this particular sort of place might have some sort of guardian spirit that keeps things in order to some degree.