First of all, let me extend my thanks to the elusive group know only as Light Novel Translations. After waiting for so many years I had long given up on seeing these books fully translated. This group is nigh impossible to find on Google or DDG due to their painfully generic name, but it is well worth tracking down the translations.
I now appreciate what a classic these novels are. I remember when I read the first book as a teenager I loved Kujo and Victorique as a couple, but I thought the detective / mystery solving part was a bit weak. I was correct, it is a bit weak, but having finished all the books, the true overarching plot is a). the approaching fictionalized WWII in fantasy legally-distinct Europe and b). Kujo and Victorique's relationship. Those plot lines are both well told with excellent endings.
I would also say the quality of the story telling and writing gradually improves so that the weakest books are near the beginning (book 1 and 3 are the weakest in my opinion) and the last few books held stories that took my breath away. As the ending approaches, all of the characters (main and side) come together for a grand finale that sweeps across the entire world. Scope of the story, richness of the setting, the writing, characters, and ending are all the best of the best. I will never forget Kujo and Victorique. And what a touching, romantic, exciting, and memorable epilogue we get at the end.
When you finish a story like this, you just wish you could stay in the world with these characters a little longer. To see just a little more of their love and their lives. How lucky then that the writer, Sakuraba Kazuki, is now writing a few post-ending novels (!) so we get more fan service and more of Kuji and Victorique. How wonderful... I step outside after reading these novels and think "what a beautiful world we live in."