This was ported from GConf, but GSettings doesn't work that way.
Settings locations are defined at compile time and can't be
relocated at run time (unless you make all of the settings
explicitly relocatable. That however is not how GSettings is meant to be
used.)
_("Log level overrides, of the form \"modulename={debug,info,warn,crit,error}\"\nExamples: \"--log qof=debug\" or \"--log gnc.backend.file.sx=info\"\nThis can be invoked multiple times."))
("logto",bpo::value(&m_log_to_filename),
_("File to log into; defaults to \"/tmp/gnucash.trace\"; can be \"stderr\" or \"stdout\"."))