It is expected, that Expedition Magic Find bonus consists of +(0-125%) bonus of Additional Expedition Affixes and +(5-110% (max for me)) bonus of monsters complexity (+ 1-22 lvl(max for me)), so I have +235% MF and +22 monster lvl, which I see in the right corner under the minimap. But in fact I have only +125% MF bonus, if I check character details. So, there is no difference between Expedition with 235% MF bonus (which has monsters with 42 lvl, while I'm only 20) and the easiest one which has +1lvl to monsters and 125% MF bonus. As far as I can see, complexity bonus doesn't count. I have unique belt with MF bonus also, but as I can see it counts right.

Screenshots will explain it much better:

https://imgur.com/a/4DHAYCG