Selecting 'No language' from styles advanced options really exports the tag to EN in PDF
When you have a document with multiple languages and the main language isn't available in InDesign's presets, ie the document is mainly in Kirundi or Samoan and there are some English phrases, a user should be able to select 'No language' from the style's advanced options. Instead, 'No language' will export as EN and the tag in the PDF will have EN listed as the language in the tag's properties. This is problematic because the tag's language will override the document's language properties. This is a clear failure of WCAG SC 3.1.2 (language of parts).
A screen reader won't be able to read the document because the English language tag properties will override everything.
Fixing this will ensure PDFs can be accessible to people who use screen readers in languages other than InDesign's presets.
On the one hand, please fix the error that a wrong language flag (en) is added to the content which uses "No language" in ID.
On the other hand, InDesign should be enhanced with missing language options.