Is your feature request related to a problem? Please describe.
Alt text should be translated for a multilingual website to maintain accessibility and SEO for each language, so it makes sense to create plugin fields for each language in the studio.

Describe the solution you'd like
The solution is very simple, for each language you are using in the studio you need to generate the tab containing the plugin fields.

I found this plugin (sanity-plugin-media fork) which is already a good base to start with: https://github.com/DavithkbY/sanity-plugin-media-i18n

This plugin uses the recommended sanity scheme: https://www.sanity.io/docs/studio/localization#k4da239411955

const locales = [{name: 'English', id: 'en'}, {name: 'Dutch', id: 'nl'}]

export default defineConfig({
  plugins: [
    media({
      locales: locales,
    })
  ]
})

I think it's best to have another version of DialogAssetEdit if locales is inserted so you can work with locales and not create confusion