The "X Offset" is something we would like to include, but there doesn't seem to be a simple solution as it may cause problems with some features as Bevels etc.
Currently, to move all Segments would be the recommendable way adding a Transform Operator (to modify Translation / Padding values) after the Sequence Operator in your case.
Upon provided screen-shots, I guess you're using "nested" RC objects - by enabling the Deform > Nest option you should get random distribution on these. Actually, in most situations, an A2S Generator will achieve equivalent results without the need to nest multiple RailClone objects. You might consider using the Array 2S Generator instead of your current set-up.
Let me add, that in some cases, you might find a good alternative to the Randomize Operator by using a Random Parameter (which has several modes) linked to the Selector Operator.
Hope that helps.