But it took someone from that world to reach it. Before he came along, even people with the same ability had no idea his world existed other than a vague idea that there are worlds no longer within reach. You also have to account for the fact that none of the mages seem to know anything about modern science, and that would be totally out of the question if a futuristic world existed within reach. This game does a pretty good job of staying consistent with the idea that we the player are the futuristic character. The things we do in daily life are seen like a strange magic to the other characters because they've never seen anything like it before.If you think that the dev set a rule that lost worlds can't be accessed, the dev already threw that rule aside when he allowed the MC to access his own lost world. But I think that rule was something you implied rather than it being directly stated. Azraesha can't access the lost worlds, the MC seems perfectly able to.
Also keep in mind the start of the game. Some kind of incident involving a poorly understood energy source tore our character out of our world and caused/awakened archmage level power in him, and is possibly the reason that world can be reached at all in the first place. Even when going back and said to have the power to rival the strongest of mages, our character is limited in where he can appear. It wouldn't be impossible to have a futuristic character, as a similar event could theoretically happen in a world more advanced than our own, but it would have to be a totally different situation and explanation from how the rest of the group were brought in.
Personally, I like how it is going so far. Modern technology is amazing, it just gets taken for granted more often than not, so I really enjoy getting to see the little interactions and exchanges that come from having fantasy characters and magic mixing with a unique magically modern setting without having the fantasy characters originating in the modern setting.