Here are my non-expert thoughts after reading about the plays and literature that used Semanthe. These plays were sort of like how
Terry Pratchett writes fantasy. They seemed to use a classical Greek or Persian setting and characters to tell new stories about current (1600 and 1700s) politics and social commentary. Or like the Bridgerton TV show, historical accuracy is not required or expected. But I'm sure we will see more Regency themed media using the name
Hyacinth even if it wasn't a common woman's name during the period. It's just become a name that now 'sounds appropriate for the era' and so will be chosen more often.
I came across other invented names too. I'm pretty sure Cleomelia was invented, but seems believable. Some invented names just sound so convincing as established or historical names. It's the reverse
Tiffany problem.