the authore is able to deliver the passage of time quite well.
Some things are just not possible on your own. No kind of teleportation or other travel-worthy magic seems to exist here and even if he did have the kind of expertise needed to design and implement a modern world-like transit method, he'd need an entire nation to get involved with it, functionally jump-starting an industrial revolution. Currently he's averse to intervening even in life or death matters for a nation he supposedly favours, so causing such a huge civilizational shift is most likely out of the question.The people that he cares about are going to pass much sooner than him anyway, so might as well spend as much time with them as possible before they die.
MC should just stop wasting so much time travelling. Are you telling me that with all his power and knowledge, the best means for travel that he can come up with are walking and riding a horse?