Ugh. If they had stopped at Yes, we'd be fine, but this additional information makes it seem like they do not permit modification of the dataset at all, outside of compression, CRLF, or character encoding.
Can you ask them this, so that we don't have ambiguity here?
Do you grant permission to modify the datasets within the GAP transitive group library (as permitted by the Artistic 2.0 License)? We do not
have any immediate need to do this, but a library without the permission to modify is not considered a Free Software component. You can
require that modified versions do not refer to themselves by the name given to the unmodified original work, this would not make the library
non-Free Software.
If they need to talk to me, I'm happy to engage.
~tom