How do I test different configurations which are set at Rails boot time?

I'm currently working on a fix related to an issue in spree commerce: https://github.com/spree/spree/issues/12231

To test the failing behavior before I apply my fix, I wrote a Rspec test like this:

describe 'new product creation' do
  context 'when runtime config always_use_translations is true' do
    let(:product) { build(:product, stores: [store]) }

    before do
      Spree::RuntimeConfig.always_use_translations = true
    end

    it 'doesnt raise NotNullViolation error' do
      expect { product.save }.not_to raise_error
    end
  end
end

But this can't work because when the test app boots up Spree::RuntimeConfig.always_use_translations is unset and the Model gets loaded with that accordingly: https://github.com/spree/spree/blob/25be0ee89d86da81b2b624405475cf48b5195a85/core/app/models/spree/product.rb#L47
Changing Spree::RuntimeConfig.always_use_translations = true never reaches through the already loaded Model. Unless I can reload it somehow?
Since in Rails.env.test the config.enable_reloading = false I had no luck trying something eg. Rails.application.reloader.reload! to get the Model reloaded after I set the configuration in the before block.

The only way to get my test to do what it should was this:

describe 'new product creation' do
  context 'when runtime config always_use_translations is true' do

    before do
      Spree::RuntimeConfig.always_use_translations = true

      if defined?(Spree::Product)
        Spree.send(:remove_const, :Product)
        load File.join(Spree::Core::Engine.root, 'app/models/spree/product/webhooks.rb')
        load File.join(Spree::Core::Engine.root, 'app/models/spree/product.rb')
      end
    end

    it 'doesnt raise NotNullViolation error' do
      product = Spree::Product.new name: 'Test always_use_translations'
      expect { product.save }.not_to raise_error
    end
  end
end

But this feels not right and most important breaking other test which run after it.

Did anyone have an idea how to test something like this?