Seeing these strange fonts in Safari only
OS X builds cache files from the fonts installed on your system. Now and again these cache files can get corrupted.

Try running the following command in a Terminal window (you will be prompted for your password) and rebooting. This will remove these cache files; forcing OS X to re-generate them from scratch.

sudo atsutil databases -remove


From the atsutil man page:

databases
     will remove fontd System or User databases along with any cache
     files. Removing databases may cause the loss of font registration state:
     fonts activated outside the standard font directories, font faces dis-
     abled, and font libraries. New databases will be regenerated from fonts
     installed the standard font directories after the user logs out,
     restarts, or the fontd server is restarted.

databases [-remove | -removeUser]
    -remove remove fontd databases for active user and system (used when no
    one is logged in and some background processes).
    -removeUser remove fontd databases for the active user only.