The field order can be important depending how the program addresses the data. As DSummZZZ noted that as long as you reference just the field names it doesn't matter, but depending how your app is structured you may be running something that references the field order. I have an app that has a filter built into the various interfaces so that the user can filter a view, doc, or report to include only the records needed. This interface has valid's & descriptions that are based on DBF order.
Your need to understand how your program uses the data in all of the code to understand whether that is going to be a problem or not. Does the program import data from and ASCII file? A number of different processes may use the data different ways.
The other thing is that a index is better off if the key fields are at the top of the structure. Everything is better faster & quicker.