Be careful.. there are V1 and V2 versions of the conversion routines. And only V2 is being tested.
geometry-utils
geometry-utils-V2
I see the confusion. The entitiesFromSolids function is not well documented.
The function signiture is:
const entitiesFromSolids = (params, solids)
And solids must be a single V2 geometry or an array of V2 geometry.