IMHO implementing back/forward would basically mean going back in the git reflog history (it would checkout, not just select the previously checked-out commit)

Actually implementing back/forward would be a great way to give acces to the reflog (it could work like browser history: a long click could provide fast access to the last few entries).

Maybe there could be a SmartGit global option to consider remotes at some specific host as "gerrit" remotes ? Something like a "gerrit" hosting provider ?

Indeed it misses the ability to resolve "interactive" rebase conflicts. That's the major missing piece that requires me to use the command line to rebase.

Also, additionally to the "squash commits" command, there could be a "fixup into (previous commit)" command (most of my squashes are fixups).

I don't feel the need to schedule multiple changes simultaneously like in the git CLI. In a GUI, reorganizing commits as I move them around seems more appropriate.