I’m not sure that I understand the question. But then I never use aliases, and the documentation is (as far as I can see) a bit terse on them.
What are “aliases in a group”? I see that I can set aliases for records, and presumably for groups. Now, do you want to get the aliases that are defined for this group? Or do you want all alises for all records in this group? Or something else?
A script could perhaps do that, but again: the documentation is not very clear (to me) on that. It says that the aliases property lists the “Wiki aliases (separated by commas or semicolons) of a record”, but is that the same as the “Aliases” I see in the inspector pane (then why is it called simply alias once and “Wiki alias” the other time)? Something else (then how would I go about getting the non-Wiki aliases)?