The
Francisca Cahill series by Brenda Joyce is gaslight London and follows a single heroine for 9 books. The
Company of Rogues regency series by Jo Beverly are about friends of friends where the stars of one novel play bit parts in others for 15+ books. The
Bastion Club by Stephanie Laurens and
Bridgerton by Juila Quinn are similar. I'd lump all the authors in with Evanovich's historicals for style and all have huge backlists for further exploration.
IIRC they are not as clean as Signet/Zebra Regency books but not as sex filled as more modern novels so I'm not sure if they'll pass the 'Christian' test. None is pioneer but London urban.