There's a scam artist pretending to be a medium.
Also, an engagement is ended but both parties have fallen in love with other people, so it isn't really a "betrayal"
A cat is believed drowned early on, but rescued and reappears midway through.
The historical practice of drowning kittens to reduce the population in victorian england is referenced several times and central to the storyline. In the very end we discover that kittens can be rescued before drowning and given loving homes in the future, where cats are extinct.
There are no emotional animal deaths or almost deaths that pull at heartstrings.
I don't know why some people say yes.
None of the named characters dies or loses a child.
There are mentions of air raids and numbers of people who died but it's in a historic sense.
No, but characters believe that they can speak to ghosts through seances and believe in the science of the "otherworld". the author makes it obvious it is not ghosts.
References are made to historical incidents including plane crashes and wartime bombings, some of which are visited by time travelers. I don't recall them witnessing a plane crash specifically.