Hey there @Kelibran! Welcome to the community! Since every version of Unreal blueprints are specific to their version and need to be tailored to it to be read correctly. The version Metahumans originally released under was 4.26 if I remember correctly, so they never innately compatible to begin with and that would require backporting.
That said, if you export the skeletal meshes themselves you would be able to import them to 4.7 however you wouldn’t retain all of the features.