Regarding shared folders location, as others members mentioned, it can be done at install time from anaconda (CentOS) installer by assigning a mount point for /var/lib/nethserver/ibay (or for /var or /var/lib/nethserver); or afterwards by editing fstab adding a bind mount. On most cases this only needs to be done one time (CLI) and shared folders can be created/deleted/managed from the UI.
Another option (haven’t tried but it should be possible), using a separate UI, could be to use cockpit side by side with current UI. Do note it’s a preview module and still to decide if/when/how current modules will be migrated to cockpit.
On the other hand, it’s more than likely that when problems arise (depending on the kind of problem) whoever is in charge of the server will need to use the command line, or get professional support (subscription plan) if that’s a stopping point.
I can understand if neither of those options is quite the solution you’re looking for.
Whichever server solution you finally choose another thing to consider is whether going bare-metal or coupling the server OS with Proxmox (or another virtualisation solution).