It was due to a bug - it seems - in Syncfusion, where the DocToPDFConverter though it was a trial version. When trial all fonts are Time New Roman (not documented)
Updating to 17.3460.0.28 solved the problem
SRSuganya Rathinam Syncfusion Team November 19, 2019 06:01 AM
Thanks for the update.
We are happy to hear that the mentioned issue is resolved when upgrading to our latest version 18.104.22.168. Please let us know if you need any further assistance. We would be happy to assist you as always.