I am using Google Noto Sans and Indian Type Foundry Poppins with FrameMaker 2019 (126.96.36.1991) on Windows 10. When using Save As PDF or Publish to PDF using the new PDF engine (not distiller) the SemiBold and Light fonts are appearing as a thicker weight. Opening the PDF in Adobe Illustrator, I can see that the affected fonts have a stroke outline with a non-zero width that is making the characters appear bolder. Italic versions of the fonts in the PDF also appear to have a larger skew angle, suggesting that it is an oblique.
Using FrameMaker 2017 (188.8.131.521) on the same computer creates a PDF with the correct font weights and italics.