How do I reduce the speed which actors can move backwards. Currently they seem to run backwards at normal speed and I would like to reduce this. I looked through the game settings but couldn't find any related to this.

You can edit the kf files with the backwards animations, or add an ability to everyone that has Reduce Speed Multiplier, Condition: IsMoving Backwards. The latter will have a performance hit, the former's a bit more challenging.

Ah yes I forgot that IsMoving could check for different directions. I already have a script that walks through refs and gives actors a scripted ability so I guess I could do it through that but I think it might be a bit awkward.

I wouldn't really know where to start when editing kf files. I don't suppose this could be done from within the GECK? What about making a copy of the walk back animation and then replace the run back animation with the copy? Would that make them walk back, instead of run?

Yep, copying the walk anim would work. You might need to open it in NifSkope and change the name from Walk to Run there too but otherwise it'd work fine.

Alright thanks I'll take a look