Finsky, have you ever propped up the inner cover at all and if so, what did you find? .
I do not quite understand but is it a bigger gap between frames and inner cover?
The system must be so that inner covers insulation must be better than in sidewalls.
When inner cover is warmest place, it does not condensate moisture.
Sidewalls can condensate moisture and the water goes to the bottom.
The upper entrance is essential with solid bottom.
But after cleansing, when bees start to rear brood, they raise the the temp from 23 to 32, and hive will be dry without upper entrance, It even makes bees feel better in their box.