I’ve never actually needed to do anything like that (so I hope I’m wrong on this) but, as best I can figure out, it’s not actually possible to do what you’re trying to achieve . . . not with a single *stat_chart anyway.
The problem is, within a *stat_chart you are restricted to using only ‘percent’, ‘text’ or ‘opposed_pair’, so you cannot even use an *if (gender condition) within a single chart, which would at least have allowed for some flexibility.
Your only alternative as far as I can see is to do it as two separate *stat_charts, duplicating all the information contained therein but at least allowing you to hard-code that single name difference within each one, e.g.
*if (gender_female)
*stat_chart
percent relaharlan Harlan
percent relanila Nila
percent relaserv Jill
percent relaorion Orion
*if (gender_male)
*stat_chart
percent relaharlan Harlan
percent relanila Nila
percent relaserv Jack
percent relaorion Orion
It doesn’t however help you much if you planned to have many such differences, but it would at least serve for one crucial difference.