This is my first introduction to D&D 5E (coming from Pathfinder Kingmaker) and a lot of the rules seemed to be slimmed down (maybe to speed up the board games) in comparison. It is a bit weird that your fighter/mage/cleric pretty much start with the same fighting capability...in fact if you happened to put more strength on your cleric than your fighter you may find that they do better in combat; or if your Elf Wizard has higher dexterity then your Ranger they will be better with a bow (at least until level 5 where fighting classes Ranger/Paladin/Fighter get an extra attack).
As for those ability checks that are used in conversation and not using the character best suited, I have noticed this a few times; it almost seems like a bug though, where sometimes your characters personalities seem to change for no rhyme or reason...I really, really hope that they fix the characters bipolar personalities since it can really ruin some of the banter in the game. My Orcish speaking high elf was all cordial and friendly with the Orcs, then suddenly decided she was all murder every last of them for no reason whatsoever, completely ruined the moment as I was starting to get attached to the character personalities at that point.
With Rogues, I'm pretty sure thieves tools help for you to disarm traps, but the perception skill (finding the trap) is tied to Wisdom, so while a little weird, your Cleric may spot traps before your Rogue. Still I would think the thieves tool should give a much bigger bonus to disarming traps then your Cleric without the thieves tool would...I probably need to look it up though since I don't really know.
https://www.5esrd.com/gamemastering/traps/
Reading this it seems like you do need Wisdom (Perception) to detect the trap, Intelligence (Investigation) check to see what needs to be done to disable it and then a Dexterity (Thieves tools) check to sabotage the trap...but I don't know what parts are implemented in the game, since the character creation screen indicated that the "Investigation" skill wasn't implemented in the main campaign.
Do really agree on the polish point...this game shouldn't of been released finished in it's current form (ie released as an open Beta on GOG). There are mistakes with spell descriptions, non-working spells/items, problems with pathfinding using the Fly spell (one of the coolest additions to a turn-based RPG), equipment that will corrupt your save if equipped. I noticed reloading a level-up save with my Ranger will result in scrambling the Favoured enemy/terrain (I reported this bug though), and of course the broken dialogue; an early example is during the very first meeting with the council, one of your party members blurts out "Pipe Down!" for no reason at all, no one is speaking or anything, it was really rather odd.
They do have the beta 1.0.22 version, but unfortunately it is only on Steam, even with Beta channel on within Galaxy there isn't any update yet from 1.0.18F