Glad to see someone working with Unreal Engine! Are you using UE4 or UE5?
Did not encounter any bugs in the demo.
I liked how you could reroll Adventurer stats if the current batch didn't seem very good.
There are a couple spelling errors.
"Adventuerer" should be "Adventurer" (Generate Adventurer screen)
"Consituion" should be "Constitution" (Stats sidebar)
"Improtant" should be "Important" (READ ME signs)
"Expodition" should be "Expedition" (Build menu)
It's not very obvious that you can scroll through the buildings. My first time playing I completely missed the Expedition Center and thought the demo just consisted of building placement. I only caught my mistake because I saw your Youtube video which clearly showed there was more to the demo than I thought. So I tried it again and sure enough, the Expedition Center build option was hiding out of view on one of the menus. I would recommend widening/enlarging the build menu so that all building options are visible at once.
Combat had a classic JRPG feel to it. I like Final Fantasy Tactics as well so I think that's some great inspiration for your game.
Looking forward to see where this goes!