[lang] attributes do not have a valid value
To create a [lang] attribute for a short piece of text
1. Go to Webflow Designer
2. Select the text you want to change the language
3. Click on Wrap with Span icon
4. Create a class name such as .language-span-wrapper
5. Click on Settings (S)
6. Click on Custom Attributes
7. Create Name = "lang"
8. Create Value = language code (ES, FR, RU)
9. Click on Save
To create a [lang] attribute for a section
1. Select the Section, give it a class, and change the attribute, as above.
Google Lighthouse says
To ensure correct pronunciation, screen readers use a different sound library for each language they support. Screen readers can switch between these language libraries easily, but only if a web page specifies which language to read for a given piece of content. If the language changes within your page, you must specify a valid BCP 47 language to ensure that the section in the new language is pronounced correctly.