Would a creature that's 180 - 210 cm tall walk and run comfortably upright for long distances if they have shorter legs than humans, no lordosis and arms (though shorter than a gibbon's) whose wrists reach their knees? Their feet are also different, having long palms, fingers, and very long thumbs, resulting all fingers being about the same length. Gibbons are mostly arboreal, but on ground are bipedal. They are however very short and light, and their walking style is quite awkward. I thought that making the creatures' legs straighter (like humans') would help... I'm not really trying to make them walk and stand like humans do, just run and walk bipedally without being super slow or jumping from place to place despite their size. They're semi arboreal too, but have to travel long distances on foot and am not sure how a creature of this size and with such long arms could pull that off bipedally.
I would think yes, But in addition to modifying the legs you'll need to change the hip structure.
As one of your commenters pointed out - there is also a very real difference in the feet. These changes are also going to impact their social structure.
No evolutionary change happens in isolation - there are always ripples. Some big, some small.
As you note, gibbons already walk bipedally when not in trees and don't have a huge problem. Bipedalism is thought to be an ancestral ape locomotory pattern when not in trees, gorillas and chimps merely became specialized for knuckle-walking independently and humans became obligate bipeds.
The long arms won't be a problem, human arms are incredibly short relative to our height (they only reach the crotch) and you could make them a lot longer before you run into problems).
Lack of lordosis is going to be your biggest problem. The entire point of lordosis is to redistribute the weight of the spine in a manner that allows the animal to stand bipedally. The lack of lordosis is one reason why other apes are such poor bipeds. Indeed, looking at the cited paper in the link, non-bipedal apes even develop a lordosis when they are taught to walk bipedally for long periods of time, so it might not just be evolutionary but reinforced by developmental. loading patterns.