Yes, it did have a certain Agatha Christie vibe but sexier.
"Sapphire and Steele" was a sci-fi show about two operatives protecting time:
https://en.wikipedia.org/wiki/Sapphire_%26_Steel
Maybe because Rommie was the ship's avatar. And wasn't there this one season where they created another avatar, Doyle played by Brandy Ledford, because Rommie went all evil (and Lexa Doig was pregnant).
Ah, I think there was one episode where you could deduce certain things and there was a lot of fanfic around it.
But yes I guess Tyr/Becca had a large fanbase but I never really bought into it.
Yeah, the Peacekeeper Wars movie was... I don't know, good to have but I would have preferred a fifth season. Obviously I also disliked how they left things with Sikozu.