We don't propagate backtraces correctly which makes things more difficult. For instance /usr/share/foreman/app/models/concerns/orchestration/tftp.rb on the line 82

81  rescue => e
82    failure _("Failed to...") % { :template_kind => os.template_kind, :e => e }
83  end

It should look like

82    failure _("Failed to...") % { :template_kind => os.template_kind, :e => e }, e

Let's review rest of the orchestration code.