Hope the devs actually read this as I've put quite some time putting it together :) Here's a bunch of both minor / major UX issues I've observed and collected during gameplay. Some of these are very minor annoyances but you know, the feel of game polish comes from reducing the number of UX annoyances to zero.

Library

1. "Unread" exclamation mark on sections doesn't disappear when you've read unread content; it only disappears if you reopen the library again

Workshop

1. Weapons don't show their type making you guess it; should show "Hand Gun" / "Heavy Gun".
2. When using a mouse, having mouse wheel scroll past the end of the weapon list feels off and doesn't allow you to quickly slow to the end as it always wraps back to start (same when wheeling in both directions).
3. Weapons would be much easier viewed as a vertical alphabet sorted list with weapon names always displayed.
4. Would be nice to have filters for damage type and weapon type (i.e. heavy/handgun and physical/elemental/etc), especially if there will be more weapons added in the future.

Game

1. There's no way to pause the game while looking at the map (only when opening character screen). Sometimes you just want to plan your next move but then the clock is ticking in the background. Perhaps the character screen should have a 'map' section/button somewhere (same as there's "Station Map").
2. Given that Tab (opening a map) doesn't pause the game, and given that the current map is not centered around the current hero, the current hero's position should be made much more visible (e.g. glowing, highlighted in a circle or something), sometimes you have a fraction of a second to quickly open a map and close it whilst fighting, and you have to be able to locate yourself immediately. Try opening the map and then almost immediately close it and see if you can pinpoint yourself.
3. "Show caption" should probably be "Show legend". ('caption' kind of implies there's captions next to objects on map, which isn't the case - hence it's more of a legend really).
4. If "caption" is not shown on the map screen, there'a big annoying "CAPTION" label (empty title) in the right corner which probably shouldn't be there at all.
5. On hero screen, various skills should probably show numbers (e.g. trap does this much damage, or this kill does this much of this type of damage). Otherwise there's no way to compare skills to weapons damage / DPS. E.g., Cartie's ult "Triggers a rolling melee attack dealing X damage that ends in an explosion dealing Y damage", where X is white and Y is orange to indicate damage types. Alternatively, if it becomes too cluttered, could add an 'hold ctrl or shift to show detailed information' which will show all details and numbers. Nerds will be happy.
6. There's no command "protect crystal bot". This would be useful in solo when you want the other hero to escort the bot while you're running around defending generators and whatnot.
7. 'Follow me / don't follow me' is not stateless. You need to remember which state you're currently in in order to issue a command; this may end up in mistakes during messy fights or escorting the bot. Would be nice to either have separate keyboard shortcuts for that or separate ui commands in some way.
8. Do duplicate steles make sense? Had two steles with identical effects (stun every 3s) in two neighboring rooms.
9. It's unclear what uncommon/rare/epic/endless mean other than some stat scaling, and by how much stats are scaled, and whether there's any randomization or not. Perhaps endless/epic should have an added random effect (given their rarity, that might be a great addendum, adding more diversity to runs; however, then there should be probably some hard lower limits on epic/endless items found per run, e.g. at least 1 guaranteed per 1/2 floors)? It might also be nice to show by how much an item is improved over common (in total %, or +% for each stat), to give some numeric insight into it. Is there a concept of a 'good roll' or not? Should there be?
10. (More of a discussion; not a suggestion really) It would be much less stressful and remove unneded uncertainty if there was no realtime clock (especially given there's no strict countdown to next wave). I.e., if a wave could be only triggered by you doing something and not by an invisible clock randomly counting down to zero after you've breached some danger threshold by opening a door half a minute prior to that. This also solves the problem of not being able to pause to view the current map. Alternatively, if the random realtime clock has to be there, some added determinism/transparency would be nice, would make the runs feel more strategic and less random.
11. Allow doing something with weapons we don't need? Even disassembling for 1 industry (or random) point would feel better than just leaving them lying on the floor.

Settings

1. If you override 'weapon switch' shortcut (which is mousewheel scroll by default), you can't set it back unless you reset all keyboard shortcuts, because mousewheel keeps scrolling the list of shortcuts in the background.
2. Using mousewheel to switch weapons is not too ergonomic because it's not 'stateless' - you need to know which weapon you're using to switch to another one; plus it's easy to scroll past the weapon you want. There should be shortcuts "Switch to First Weapon", "Switch to Second Weapon".
3. It would be nice if the game allowed two shortcuts per binding, like many games do. E.g. allow mousewheel scroll for switching weapons, but also a hotkey.
4. Pressing F to restore keyboard shortcuts should ask for a confirmation so that you can't erase it all accidentally.

Starting a Run

1. Sweeper is always focused when starting a run, because his icon is the first in the list; this is a very minor, but would be cleaner if no hero was selected, showing you just empty hero slots. Minor annoynance but still.
2. The information show in 'Show details' is too poor compared to what you see in game when you press Esc. It should display all the stats like Wit, Speed, etc.
3. If using the mouse only, sometimes there's no way to 'Show details' without first locking the hero - try doing it for Cartie (it feels a bit clunky, plus the Show details button is at the very bottom of the screen which is not too ergonomic either when using a mouse). Having to lock the hero in just in order to be able to click that button feels a bit off ux-wise. Why is this 'show details' needed when there's lots of empty space on the right of the screen that can be used when hovered over?
4. Would be nice if it was showing what are the current quests each hero has (could be shown on the right hand side when focused / hovered over). Additionally, could highlight the quests either directly related to the starting zone or can be completed if starting from this zone (e.g. on floor 2).

Finishing a Run

1. Would be cool to see lots of more detailed nerdy stats, like damage done by each hero, by turrets, breakdowns by damage type etc, healing done, upgrades bought, weapons found, turrets built, and whatever else that can be tracked as a number.

Hacking Post

1. After clicking around a bit, mouse-scrolling in "Ongoing Quests" panel randomly (but consistently) stops working.
2. Icons for completion items above monster types are not explained and are not immediately obvious.