as mentioned in my message the scale is off by 1 / 2.539998628400741.
this ratio match the inch / cm ratio where 1 inch is 2.54 cm.
I think the issue is Datasmith takes the size of the model in inches and converts it to 1 inch = 1 unit
that would result in 100x100x100cm being reduced to ~39x39x39 units.
more details here:
https://forums.unrealengine.com/unreal-engine/unreal-studio/1528499-datasmith-sketchup-scale-bug