We had already noticed this and worked on fixing it. I can see that we made an error linking one of the techs so that it's already known, we'll fix that for the next update.
Artillery has already been fixed in a previous update, it's a prereq for Grenade Fusing so the US inherits the tech. I suspect your savegame was started with an older version of the game.
...I know it is time consuming...
Then I would hope you wouldn't be rude by calling our hard work a beta. Reminder, there is one rule on these forums - be polite. Consider this a polite reminder.