By my understanding, if you want staff users to be able to browse the trainee user homes, then it's essentially doing the basics of what you want. From my understanding it's giving access to the directory where all the home directories are stored.

If you want the trainee user shares mapped individually, then I'm pretty sure that what you'll need to do is configure that manually. By default user home dirs are designed to be private.

Manual config could be done server side, by configuring each user share individually. Or you could configure it client side (e.g. a Windows log-in script that all the staff users have) which maps all the trainee users homes for each staff user.

Having said that, I haven't used Windows much for years and beyond release testing having had tons of experience with Samba. Perhaps it'd be worth asking an expert Samba user? One of the Stack exchange sites, or the Samba mailing list might be good options? If you manage to work it out, please post back as it would be useful info for me and no doubt others too.