Actually I find it very strange that ribbons on this bar looks so fresh but metal is quite a damaged by age..
Another one strange issue is that this purely bavarian bar (EK on 2nd place) is done in purely prussian triangular manner..
And finally - I have never seen 3rd one medal in this bar..
I wouldn't be troubled by the Prussian-style trapezoidal mounting. Specialized businesses at the time offered different mounting styles for the customers to chose from, and it is entirely possible that this was simply the wearer's personal preference. (Active military personnel had to follow military regulations when it came to the mounting and wearing of decorations, but veterans who had long since returned to civilian life had much more liberty in this respect.)
I don't find the difference in wear and age between the medals and the ribbons to be so distinct as to be implausible, either, although, with this mounting style, it is of course no problem to add/remove/switch the medals, making it hard to tell with absolute certainty that a medal is original to a bar.
Which brings us to the third medal... I must admit, I don't recognize that one, either. The ribbon looks like that of the Hessische Tapferkeitsmedaille [Hessian Bravery Medal] to me, but that is not the decoration seen here. Would it be possible to post a close-up of the reverse side? I can't read the inscriptions on the arms of the cross; they might be helpful in identifying it.