I am PRETTY sure that I have now won the "Era-upgrade" for my Pollux engine THREE times... instead of upgrading a ... well, "dire needed" other update. (Like tractive force...)
Please, have a look at this. -this should not be.
All in all, I think you have to adjust the wins for tractive force just a tiiiiny little bit.
If I look at 18 videos per day... I think it's silly to get into the endgame with a "Bonus engine" that can pull only 3 wagons, after having watched 750+ videos !!!
I get the idea, where you are aiming at... but, it is a weird idea.
(If I know the core-community right, it will become a trend -quite soon- to just park the engine in era 1).