Thank you for reaching out to us. We are sorry for your difficulties as the fonts are not showing up in your email client after you import it. To investigate the issue could you please let us know the email client you are using as some email clients do not support HTML email or web fonts in email. Please refer to the below article to help you understand usage of web fonts in HTML email or newsletters.
Please let us know if this helps. Please feel free to reach out to us anytime.