Why don't you extract the License-field from *.rpms and check if they comply to the new rules?

It would work for cases like GPLv2 -> GPL-2.0-only.

But you can have cases like:

    MIT -> MIT 

    MIT -> MIT-Modern-Variant

so at the end you want to check %changelog and dist-git log. If there is no entry in one of these two changelogs and license is MIT then I assume it is Callaway MIT. If there is an entry that mention spdx then I assume it is SPDX MIT.

Miroslav