I don't think what you say is accurate. I maintain an Elm app and it is fully localized and I think it has a pretty good accessibility

Localization is done using one big record for each language, that I just pass into each part of the aplication that uses strings. It's very convenient cause I can use simple functions in the record where they make sense for plurals and special cases in different langauges

Accessiblity is achieved with a combination of good html, ports and in some complicated cases (autocomplete-typeahead) - web components