Missing Files renamed by FCP

Did you try relinking? File->Relink Files, select "Missing" and click Locate; then select a folder containing the files, and click Relink.

By the way, renaming of files like this usually happens when there are files with the same names, and it usually does not cause them to appear offline.

You do not relink Proxy files, you delete them and regenerate them. You only relink original files. This is actually a replicated post, since you've already addressed this issue in your previous post. In the previous post, you mentioned there are files missing. Look for those, ignore this naming stuff, it is not your issue.