My apologies for the confusion - as Bertram says, I did have the incorrect element unit panel open - the correct one is posted in the original message above.
Now you can see what I mean about supermen - check out those stats! The regiment is hereby officially renamed the "2nd Bn Prinz Louis' Superheroes".
I suspect this had to do with heavy casualties - after the battles in Saxony, this bde was whittled down to a handful of lucky and battle-hardened survivors. I pulled them back to Prague for R&R, gradually built the bde back up to strength, but apparently some bug has exaggerated their experience bonuses.
(p.s. Bertram - how about a battle of champions? You select your best bn, we'll meet on neutral ground. You win, I'll leave you Prague without a garrison. I win, you do the same with Berlin.