Windows chkdsk replaced bad cluster - are files now corrupted?

The answer is, it depends. the file was at least in part occupying a bad cluster, which in effect corrupted the file. chkdsk reallocated the sector (pointed that address to a not-bad location on the disk surface) and attempted to copy the contents of the bad cluster to it. there is no guarantee however that the data in the source cluster could be fully recovered to the destination. if it was, your file is intact, but if it wasn't possible to recover the data completely and accurately, there will have been some corruption.

unfourtunately, without a baseline, there is no way to tell.