Can you / have you tried v.6+ to open the 5.4.1 project?
The release notes for v.6.0.7 here
- imply that there was a change in RW file formats.
So I would try installing perhaps the latest of the v6 series then opening your 5.4.1 file and then saving it into the v6 format as mentioned in the release notes. You should then be able to open the new project file in v7.
The earlier versions are available from the Realmac site via the links in the release note file.
If you are unable to install the earlier version then it may be that someone on here might be able to do the conversion for you.
If you are going to do the conversion yourself then I strongly advise reading the release notes to confirm that what I’m saying will work for you. Obviously keep backups of all project files so that you can revert back if needed.
Hope that helps a little.