Rosemary is one of my all time favorite Regency authors, and she's a good mystery writer as well. It's an odd read. It keeps veering between the sorcery, Regency, and romance genre imperatives. It's also strange because the audience is not a specific demographic so there are sudden expository lumps all over the place. But the disturbing part, the part that made me seriously lose my sense of wonder, are the names.
Names are critically important in maintaining atmosphere in a novel.
The introduction of a jarringly contemporary name in an historical context, even with the excuse of time travel, ruins the fantasy. It's not Scandanavian, and it's a modern name, and it's just plain goofy. And if you're going to give people lists of middle names to imply aristocratic blood, please don't use Dowsabelle for a Regency duchess. I started laughing out loud, not the reaction I think they had in mind. I hate when authors make a misstep like that.