You don't mention whether the problem only manifests when the file is printed or also when it is viewed.
Either way, as far as I am aware, the Steiner pages have the fonts embedded in the PDF file, therefore, it is not necessary for the fonts to be installed on the user's computer.
Assuming that it is only when printed, it is probably that a setting has changed as a result of an operating system or printer driver update.
When ready to print your PDF, in the printer dialogue box select the printer properties. You should see something similar to this, but it is very much printer dependent as to the exact layout.
Under that advanced tab, there is a "Specify Font" button, pressing this displays the "Specify Font" dialogue box which is shown open in the image.
You want to select: "Always Use TrueType Fonts" rather than the "Substitute TrueType Fonts with Printer Fonts" which is currently selected in the image.
Unfortunately, this only gives the general idea, as the location and the exact wording of the buttons, tabs and options will depend on your printer and operating system version.
Hopefully, this helps in getting your problem solved,