From my understanding of Caecilia this is not a font family with regular / bold / italics / bold italics, but four different fonts. And as they are already bold and heavy types, there is no "bolder" type available.
I have PMN Caecilia 75 bold (only one font type) installed and it supports italics, but you are true, bold is not shown.
Maybe have a look
here with several Ceacilia fonts, maybe you'll find one who matches your needs
As for the question, why only two of the four Fonts are displayed, I have no clue. Maybe corrupted data?