Does it bother you to sit backwards on a train?

No. 

I prefer sitting backwards on the train and will always choose it if I’m not in an assigned seat. 

It does not bother me. I'd often sit backwards on Amtrak going from Sacramento to the Bay Area (and sit forwards going the other way). As long as I got to sit forwards on one of the trips, I was fine. 

  I don't prefer it.  If it's the only option, I choose to stand instead.

~

I would not be able to.

I never noticed.  I do not go out of my way to look for things I can be disappointed about.  Unless it causes "car sickness" WHO GIVES A HOOT?

I never noticed this until you mentioned it.

I don't like it, but if there are no forward facing seats I will sit there.

I prefer forwards facing but my allocated seats for both outwards and return of a long journey I made last week were both rear facing. (Three and a half hours for that section, the whole trip using 3 separate trains.)

I prefer the window seat though. My journeys are not across vast empty plains, so I am more interested in the scenery than, say, reading. Further, I refuse point-blank to join the herd unable to travel more than three and a half minutes without immersion in a box of electronics! I don't own a lap-top anyway, and though I had my phone with me, I left it switched off for almost the entire three days I was away.

They are encouraged by modern railway coaches, on the main-line services at least, having Wi-Fi connections and standard mains sockets (for power-supplies and chargers). 

At least the modern headphones don't subject everyone within a several yards radius with that annoying, rhythmic, sibilant "psst-psst-psst" sound the older versions leaked. 

Something I have found though, if rearwards-facing but next to the window, I've tendency to try to look round, forwards. It's not so bad in an aisle seat, partly because if I did that I'd be staring rudely at the person opposite, but also thanks to a somewhat restricted but more balanced view out.