Just a few shell issues:
The stairs should be in_hlaalu_hall_stairsl, and the piece at the top (in_hlaalu_hall_center) next to it should be in_hlaalu_hall_3way. This gets rid of the caspering, which is where you can see an untextured side of the asset and so see through it. As it is now you can see through the wall if you're stood on the stairs.
Also, the in_hlaalu_doorjamb should be swapped for in_hlaalu_doorjamb_load to match the doors in them.

I'll do a full review once that's sorted.

The cell now appears to be off grid, if you select one tile with the gridsnap set to 64 it should snap to the rest of them but it appears the shell has come off the grid at some point. This can be verified by double clicking a tile and checking the coordinates, you'll see that they have decimals which should not be the case if they are snapped correctly.
Most of the objects on the floor are bleeding though the floor, which may be a consequence of this. I would fix the snapping of the cell pieces and then have another go voer the item placements to make sure ntohing is bleeding or floating.
The lighting is mostly fine, but the ambient red should be increased by 10 and the ambient blue & green should be dropped by 10.
Additionally the sunlight is very high, halve all the sunlight values.
The bookshelf used is a furnR bookshelf, the R here means rich and indiciates what type of set it is. This cell must be entirely furnP, as it is a poor interior.

The tile at the top that should have been in_hlaalu_hall_3way, as mentioned above, is in_hlaalu_room_door1 and a post has been added to hide the missing pillar corner. in_hlaalu_hall_3way has a pillar on both corners which fills that gap. Delete the post and replace the tile.

Reviewed:

Name: PC_Kalinnikov_Showcase, was made for the PC forums so this is fine. Claimant is aware TR cells would have the TR_ prefix.

Clean: No, needs cleaning.

Lighting: No issues, nice.

Northmarker: Present, good.

Fits exterior: Yes, fits to a ex_hlaalu_b_22. Good

Pathgrid: Needs updating to match changes to the shell.

Illegal to Sleep Here: Yes, good.

Gridsnap: Correct, good.

Bleeders:
com_basket_01_chpfood, through the tapestry behind it.
com_sack_01_saltrice_10 x 2, the corners poke into the crates next to them slightly.
crate_01_food, through the same tapestry as the basket (For this zone I'd advise swapping one of the crates for another basket, there's not quite enough space for everything)
furn_de_p_table_06, slightly bleeding through the ground.
misc_com_bucket_01, slighty into the ground
Misc_Com_Redware_Cup, into the table
misc_com_redware_plate, into the table
Misc_SoulGem_Petty, into the shelf

Floaters:
All objects on top of the two furn_de_p_shelf_02 need F-dropping, they're all slightly hovering.
com_sack_03_chpfood5
com_sack_03_ingredients
common_belt_01
ingred_ash_yam_01 x 2, use ALT to place these.
ingred_bc_coda_flower, needs an f-drop
Misc_Com_Wood_Bowl_01, not tilted right, alt place this and then redo the spoon.
misc_com_wood_spoon_01, the one not in the bowl. Set the x rotation to 1.0 and lift and drop it so it sits correct on its center of gravity instead of on the back of the spoon head.
sc_paper plain x 2, paper needs to be manually set down because its bounding box is wrong so just f-dropping it causes it to float about an inch.
Misc_Quill
Misc_SoulGem_Lesser & Petty, same as with the spoon, try to rotate this so it sits naturally rather than on a point.
steel axe, about a foot off the ground.
T_Com_BrokenBottle_06, not quite rotated correctly.
T_Imp_Card_Deck_01

Other:
chest_tomb_small01 is used for tombs, swap for one of the chest_small_02 variants.
tapestries should be placed so the stick does not touch any wood, and the knot is entirely clear of the wall. As shown in the image provided below.
sacks and pillows should be bled somewhat into the surface they are on to simulate them being soft. Bleed them about 1/4 into the ground, give or take. DOn't bleed them on the seams though, so for example com_sack_03_chpfood5 should not be bled into the floor but should be bled into the wall slightly.
Swap some tapestries for another variety, having only one design feels a bit copy/paste.
Delete in_hlaalu_room_post on the top floor.
Tableware with pointed bottoms, such as misc_de_bowl_redware_01 and misc_flask_01 should be sunk to hide the point.
T_IngFood_AppleSkyrim_01, T_IngFood_CheeseNord_01, T_IngFood_Fig_Dried_01 & T_Nor_WoodenPot_03a are assets for the Skyrim and Cyrodiil project. Swap these for native Dunmer stuff.

Alright! This one makes much more sense lol.
Final few things I expect:
T_Imp_Card_Deck_01 is an imperial object for P:C, should not be in a dunmer int.
There needs to be 10 T_data assets, not counting furniture, so there needs to be 4 more added (after the cards are taken out)
The misc_de_bowl_redware_01 and misc_flask_01 should be sunk more, sink them to the bottom stripe.
Both the com_sack_01_saltrice_10 should be sunk a bit more, about a quarter of the whole model should be sunk into the surface it's on.
ingred_scuttle_01 bleeds through the bowl it's in.
com_sack_03_chpfood5 is floating above the ground.

Pathgrid will need to be redone since it appears to match the old cell layout.

All placement issues sorted, just need to make sure the pathgrid covers all of the walkable area and all the nodes are on the ground. There should be no need to move them up or down from where they appear when you right click to place them.
Included an example of how I'd do the top floor for guidance.

All issues fixed, that's a pass. Congrats!