This game is with no tech trading option on, but I can't see how far
the AIs are in research. Not in the foreign advisor screen nor when I contact
the leaders. The picture gives all the techs the human player can research.
Huayna Capac doesn't have Gunpowder, I know because the game is already
somewhere 1800 AD + "see research" from espionage, but he has researched
Education (first to Economics) and of course Guilds. So in the "can research"
colomn should Gunpowder occur.
It's misleading to see all the same tech icons for every leader in the "can research" colomn.
It simply doesn't make any sense.
you are right that this is no good - basically the can research shows you the same for all civs, probably (I don't know for sure) what you can research - the cannot trade screen shows you what of those he cannot trade - which basically tells you that he has it. Now since you already know gunpowder it doesn't show up - this is confusing, so you are right - they should update this screen to account for no trading/brokering...