How to use validations with mobility gem?

I'm trying to add validations to my mobility-powered application and i'm confused a little.Earlier I've used code like this

I18n.available_locales.each do |locale|
    validates :"name_#{locale}", presence: true, uniqueness: {scope: :animal_type}
end

And it worked fine. But in my last project it doesn't work at all. Any ideas how to perform validations? My config is below:

Mobility.configure do
  plugins do
    backend :container
    active_record
    reader
    writer
    backend_reader
    query
    cache
    presence
    locale_accessors
  end
end

UPD: I've identified my problem - it is because of , uniqueness: {scope: :animal_type}. Is it possible to use mobility with similar type of validations?

When you use uniqueness validator it uses query to the database to ensure that record haven't already taken and you get this query:

Let's assume you have Animal model

SELECT 1 AS one FROM "animals" WHERE "animals"."name_en" = "Cat" AND "animals"."animal_type" = "some_type" LIMIT 1

And of course there is no name_en field in the animals table that is why you have an error

To archive this you have to write your own validator

class CustomValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    if translation_exists?(record, attribute)
      record.errors.add(attribute, options[:message] || :taken)
    end
  end

  private

  def translation_exists?(record, attribute)
    attribute, locale = attribute.to_s.split('_')
    record.class.joins(:string_translations).exists?(
      mobility_string_translations: { locale: locale, key: attribute },
      animals: { animal_type: record.animal_type }
    )
  end
end

And then in your model do next:

I18n.available_locales.each do |locale|
  validates :"name_#{locale}", presence: true, custom: true
end