> I have made a copy of my colleague's Framemaker files ...
Any chance you could do that step again, but this time Open the original files in FM, and then save them to the new location? If so, FM updates all paths as needed.
Of course, if your CMS won't let you, and/or the original import paths are inaccessible from your system, then ignore that suggestion.
Path transformations can be scripted. See the recent discussion on Text Insets.