Bring missing translation from spree and use root namespace for translations instead of the spre namespace

app/views/spree/admin/shared/_calculator_fields.html.haml

@@ -1,8 +1,8 @@
 %fieldset#calculator_fields.no-border-bottom
-  %legend{align: "center"}= Spree.t(:calculator)
+  %legend{align: "center"}= t(:calculator)
   #preference-settings
     .field
-      = f.label(:calculator_type, Spree.t(:calculator), for: 'calc_type')
+      = f.label(:calculator_type, t(:calculator), for: 'calc_type')
       = f.select(:calculator_type, @calculators.map { |c| [c.description, c.name] }, {}, {id: 'calc_type', class: 'select2 fullwidth'})
     - if !@object.new_record?
       .field
@@ -10,4 +10,4 @@
           = f.fields_for :calculator do |calculator_form|
             = preference_fields(@object.calculator, calculator_form)
         - if @object.calculator.respond_to?(:preferences)
-          %span.calculator-settings-warning.info.warning= Spree.t(:calculator_settings_warning)
+          %span.calculator-settings-warning.info.warning= t(:calculator_settings_warning)

config/locales/en.yml

@@ -2081,6 +2081,7 @@ See the %{link} to find out more about %{sitename}'s features and to start using
   tax_category: "Tax Category"
   calculator: "Calculator"
   calculator_values: "Calculator values"
+  calculator_settings_warning: "If you are changing the calculator type, you must save first before you can edit the calculator settings"
   flat_percent_per_item: "Flat Percent (per item)"
   flat_rate_per_item: "Flat Rate (per item)"
   flat_rate_per_order: "Flat Rate (per order)"