Facebook App Font Problems

A

AC Question

Just ran into a problem with Facebook app on my Samsung Galaxy S3 over the weekend - likely due to an update.
For several months, I had successfully downloaded and installed unicode fonts (Tahoma and DeJaVu Sans), which allowed me to read posts in polytonic Greek (circumflex and grave accents, aspirations, in addition to standard accent mark). For whatever reason, FB app suddenly stopped allowing me to do so, causing boxes or blank spaces to appear in the place of accented vowels and rendering reading irritating and sometimes impossible.
I can read polytonic marks on other phone apps and even on Messenger, but not on FB app. Gmail app was also always a problem.
Why won't they change their font style to go along with the changes made to the rest of the phone?
Any advice would be appreciated.