I don't think this would be better. Then every time a new instance would be started which works indepedent of the existing one. This is especially unconvenient when opening files via the .desktop items (task bar, app menus, file managers, ...).
Agreed, we ain't gonna do that.
The socket file message probably means either Geany crashed
Does it lead to this? I don't think so
Geany was run as root or `sudo` and that still owns the socket link in your config directory.
More likely. This is another example of a misconfigured sudo that wrecks dotfiles in the user's directory */me sighs*.