As I know problem is that fsdt updater creates model.cfg with incorrect path.
That path is correct.
So each time I change it manually. It there any chance to get it finaly fixed?
There's nothing to fix, the path IS correct because, in order to have custom crew uniforms for extra liveries, the exterior XML will be copied in that new folder, so the path will reference to it.
So, the real issue might be the exterior xml hasn't been copied, which is not normal. As usual, when reporting a problem like this with a livery, please point where it can be found. Is this livery found in the PMDG installer by default, or it must be downloaded ? If it must be downloaded, please provide a link so I can test it.