The disk has been around for a while and mounted fine to date.
Your questions answered;
1 )Journaled HFS
2) The following message on attempt to manually mount.
The disk “RAW Images 3” could not be mounted.
Try running First Aid on the disk and then retry mounting.
3) Yes the option to view mounting is enabled.
The answer is in your second post "try running First Aid".
Open the applications folders and got to dik utilities. Open it and click on the drive and click on "repair". You might loose the data, so, if you have the possibility to put it in the PowerMac do it there and first save the data, if possible.
Disk utility will tell you what is wrong and what to do. But you can get back here for further questions.