The topic was closed when the problem was not resolved.
So I'm rewriting it here.
Previous topics are as follows.
https://wplms.io/support/forums/topic/certificates-of-completion-are-not-automatically-printed/
It's been 2 months, but the error on the certificate of completion still hasn't been resolved, so it's very frustrating.
I downloaded and installed the open sans font as per the link below and tested it. However, looking at Google Developer Tools, it is not changed to the changed open sans.
https://somup.com/c31u2UtRfI
https://wplms.io/support/knowledge-base/wplms-pdf-certificate-tcpdf-utf-8-bad-encoding-with-special-characters-displays-on-pdf-file/
Hi apologies for this delay , we attempted to fix it put many hours to it but the fonts didn't work .the issue seems to be with the tcpdf library .
In the meantime you can use the image certificates which has some quality issues .
for that you just need to disable the pdf certificates plugin and add a certificate using old style : https://wplms.io/support/knowledge-base/certificate-import-codes/