Unit listing customisation

Hey so at the present moment i am trying to setup a listing where a user can dictate the length in which a service can provided for. So for example Joe blogs will off 24 hour technical support for a person sharetribe open source installation, for say 3 weeks, for $100 for that period of time. Is there away to make this clear during the listing phase.
Do we have to edit the unit_listing.rb file, and change

 class ListingUnit < ApplicationRecord
      belongs_to :listing_shape
    
      validates :unit_type, inclusion: ['hour', 'day', 'night', 'week', 'month', 'custom'] -# do we change this row? 
      validates :kind, inclusion: ['time', 'quantity']
      validates :name_tr_key, presence: true, if: proc { unit_type == 'custom' }
      validates :selector_tr_key, presence: true, if: proc { unit_type == 'custom' }
      validates :quantity_selector, inclusion: [nil, '', 'none', 'number', 'day', 'night'] # in the future include :hour, :week:,:month
    
      def to_unit_hash
        {
          unit_type: unit_type,
          kind: kind,
          quantity_selector: quantity_selector,
          name_tr_key: name_tr_key,
          selector_tr_key: selector_tr_key
        }
      end
    
      def self.permitted_attributes(unit)
        HashUtils.compact(unit.slice(:unit_type, :quantity_selector, :kind, :name_tr_key, :selector_tr_key))
      end
    end

i am also trying to work out what name_tr_key, selector_tr_key and quantity_selectors are. Or maybe someone can point in the right direction to find some resources on this.
Regards,
Joshua