The XBRL feature in Business Central assumes direct presence of elements definition in schema files, not references [to other file locations] to such.
While this is allowed under Spec 2.1, BC does not support it.

Although we state that we support Spec 2.1.(which the XBRL capabilities offer do) there are multiple things possible under Spec 2.1 that BC does not support: formula linkbases, extending taxonomies (BC is not an schema/XBRL authoring tool), Custom ItemTypes, iXBRL, and embedded schema references, and a few others.