I don't think the problem with Black Geyser is with the bugs.
I fear they tried to bite a lot more than what they can actually chew. Hence the many problems the game has. Poor magic system, bad UI, combats too easy, very shallow NPCs with basically no dialogs, too many fetch quests, etc.
Biting off more than they can chew is a watchword for most of the old games that are now oft banded around as legendary classics. So not by itself an interesting criticism, even though valid, it's just something that any RPG fan really should be fully used to by now.
Regarding the list of problems:
The magic
system seemed ok to me, so you'll have to be more specific.
I didn't find the UI any better or worse than similar games in the genre. For example, I really hated Pillars of Eternity's UI with it's myriad of buttons within buttons, but I don't remember much about Pathfinder's UI, so I must have been ok with that, and, here, I don't recall battling with the UI much, so I'd class that as OK. Not amazing, but not
bad.
Yes, combat was unfortunately too easy generally, as mentioned in the review. However, it's been an awfully long time since I played a similar RPG with even slightly difficult combat. I'd be hard pressed to name any popular RPGs with tough combat on normal difficulty since about 2005, and even before that a lot weren't specialised in combat. It's a very valid complaint, don't get me wrong, but I don't think anyone expects Knight of the Chalice from popular RPGs any more. More's the pity, but it shouldn't really be a major expectation of a game in this particular niche. But, yes, I agree, probably one of the most stand-out obvious downsides of the game.
The issue of shallow NPCs is an interesting one. I mean, compared to what exactly? It's no Torment, that's for sure, but I found it adhered to a very unnoticeable and expected formula for NPCs that is not unlike hundreds of other games. Unless the developers were particularly promoting 'best dialogues ever'? Or are you just referring to the companions? If you were just referring to the companions, then, sure, that is a glaring issue for those who like that, and was addressed in the review.
Fetch quests are an interesting complaint. The game has it's share of 'get me this item please' quests, for sure. But, again, pretty much every RPG ever has similar ones and in similar quantity. Meanwhile the game does have a lot of quests that are not fetch quests, some of which are surprisingly interesting and involving. So I find it a bit rough to blame the developers for not knowing every single person's individual threshold for fetch quests. I mean, it's a valid point, but it's a point you could make about all RPGs ever, so why overly pick on this one for it?