Is there a way to change working units for a number of files in a batch process?
There is a key-in and an application that will allow you to change the units and also scale the file accordingly.
Key-in> set units MU, SU
This MicroStation V8 VBA macro ScaleFile allows you to rescale models (e.g. cells in cell libraries) using MicroStation's batch processor and a simple command.
Scale File/Model for MicroStation V8
AskInga - Change V8 Working Units by keyin