I also personally find that the MC is not really that smart and rather naive, I really feel like he thinks he's in a game or the chosen one with plot armor and even if that's the case, it's not really great for immersion, throughout the story, I feel like he clearly doesn't care about the world.
He arrived in and doesn't ask any relevant questions about how the world works, the different religions, the abbreviated history of the world, why the war with demons or even magic and the different schools... Nor the question of why only nobles can use magic ?
Basically, I find him incredibly passive. All he does is follow the trend that others impose on him.
For example, someone wants to sell him an elf with a sad little story, and he buys it because they tell him it's clearly the best solution, and he never questions it.
So, the noble sex slave trade isn't a big deal. At least I did my good deed and saved the elf. He could have chosen from the start to train even more during the week to go and destroy the traffickers' hideout instead of making fans... and solve the elf problem right away. No, he has to wait until they kidnap her to really act on the real problems.
He's always in the present, never looking to the future.
Not to mention the stupidity of creating things that come from the earth and are much more technologically advanced in a fantasy world if you want to go unnoticed, no luck, I think the other heroes will probably realize that an electric fan has no place here and probably ask questions about the creator.
And the inconsistency that says that he can only make things when he knows how it works ? So, he knows perfectly the construction from A to Z of a fan, a flashlight or even a lighter? I find it hard to believe.
Unless he just has to know very vaguely how it works for it to work, but in this case why doesn't he create firearms or even a grenade launcher for fun, just to bring "democracy" to the world... For me, his power to create earth-tech is basically perfect for destroying the genre.
He also literally has the power to create any spell, is only limited by his own imagination, and the spell he uses the most is fireball... seriously dude ?! Create fucking black holes ! Disintegrate them at the molecular level. Deflect light beams to become invisible and finally stop being tracked so easily ! Teleport a random rock directly into their brains, I don't know, do anything using more than two neurons please...
And the comments about him being a "pussy" aren't necessarily wrong, but I prefer to say that he's rather hypocritical, I mean the guy clearly doesn't care about the history of the world and races and knowing if the world is more complicated and nuanced than black and white, so killing dozens of goblins and orcs who seem to be beings with a certain level of intelligence doesn't keep him awake at night, no problem at all, they're necessarily bad, but killing a disgusting human who traffics slaves then it wavers.
The same later having a second chance after dying, cool, people smoke tobacco here too, perfect, I'm going to resume a bad habit for drugs, because I have no willpower as a human being and well cancer, it's not very serious, it can probably be cured here with a little magic, even if I have absolutely no idea, hey, I'm even going to show and explain to this unscrupulous tobacconist how to create a drug empire that will probably kill millions of people in the future. I'm a really nice guy, it should be fine.
What!? This woman, who literally stalks me for no reason other than her little interest in magic and who thinks she's absolutely untouchable, didn't hesitate for a second to kidnap me and extract secrets from me under the penalty of literally making my dick explode.
No, I can't do anything against her... even if I know she's probably not going to stop there. She's a woman, I'm weak against that...
Seriously ?! If I were in its place even if I can't kill her, I would at least ask Sylph if she could help me create a servitude contract impossible to break except for me, so that her power is greatly reduced, and she can no longer do anything to me, if she tries to talk about me to someone, she suffers if she tries to have me murdered, she will lose her life or her power completely. That's how you make her understand that she shouldn't have bothered you.
Anyway, that's all to say, I find it a shame with the potential of a universe like that we end up with an MC barely more intelligent than the Weeb Hero, and the lore is clearly pushed into the background...
Especially when I have just finished a "Dogma" or the MC even if he has problems and demons it only makes him more human and interesting, and he remains decisive and reliable in these actions.
, if it was just the protagonists... but you make it look like there is a big earth quake occuring each time 
