If you ignore something without understanding you have a problem. If you decide something isn't significant from a position of knowledge then you need to justify that. I cannot comment on interpretation: that's for you and your supervisor to figure out.
As I also don't know what the device is, it's hard to judge. To add, transient and steady refer to the solution of time. "Stationary" would translate as not moving: English isn't a simple language so I just want to clarify if parts of the solid/surface mesh are moving or not.
In terms of switching from steady to transient, there is no simple answer. If the boundaries are transient, it's more straight forward. If the transients are flow induced it depends if they matter and if they alter the answer to the question you want to solve using CFD. I may run a model that exhibits transient behaviour as steady as I don't care about small changes in the flow: if the changes are large but don't alter what I am worried about I may also neglect them. However, I've also been doing this a while so have a fairly good understanding of how something should behave.