@sjmcc13
sorry, I did't know I was talking with the author, since you know what was in the books he was reading.
MC managed to track down his bloodline and couldn't find a single hint of how the magic development was going since his time? His main focus. Also, you tell me to not assume what he knows or not while you fully assume that, instead of the author not covering a plot hole, the content of the books he have read, while getting overly excited to talk about magic just to rub our noses on what the MC's priorities are, did not have any info on magic research... How does a experienced researcher not find anything in so many books? And I point it out again, the dude found his bloodline... In a middle ages setting... And if he is reading about battles, since the books came from his brother... In a world with mages, you are telling me he didn't notice the decline in the mentions of troops used to fight? Or his brother got him a super specific book, that only have information about warriors and his own bloodline... From his father who holds pride in his mage ancestor and kicked him out for not having an affinity. Or from a MAGIC knight school? Also also, time and time again it was shown that not having an affinity and being unable to use magic are not related. So, again, this dude, with knowledge from 2 lives, is oblivious to the mention of his favorite topic in a few dozens of books and doesn't know 'common sense'?
I am not saying that this is the "ultimate trash isekai" (not that this is an isekai, before you get triggered), but it is far from the perfection you want others to interpret from your words.
The thing you like has a flaw, get over it. We are not hating on the thing, there is a plot hole and people are commenting on it. Perhaps in the future, it will be better explained. Or the author will just ignore
to force a "naive" OP reincarnated MC. Which Shikkakumon no Saikyou Kenja does a better job.