When assigning a font to any item (body, headings, links, etc.) in Jupiter X > Customize > Fonts & Typography, you may notice an issue that the font isn't updated on the front-end of your website. Mostly this happens to Elementor widgets only, not to default widgets, menu, etc. if they are not added in Elementor.
To fix this problem, you need set Elementor fonts to Default so the Typography settings take action.
1. Edit an existing page where the fonts are not applied.
2. Click on Edit with Elementor button.
3. From the Elementor's left dashboard, click on the burger icon.
4. Open Default Fonts menu.
5. Change Family setting to Default for the needed items and click on Apply button to save the changes.
After that fonts from Typography Customizer section should be applied to your elements added via Elementor page builder.