Brill typeface: Is this a Word issue, a typeface issue or a PDF creation issue?

In my pursuit of finding the typefaces that correctly render both the combining diacritics and Serbian versions of Cyrillic italics letters I've just checked how does Brill fare. Weirdly, it only fails to convert one letter properly, but what is weird is that even though the letters appear correctly in Word, they do not when one creates a PDF.

Why does it happen?

The only typefaces that manage to do these things correctly are two SIL ones, even ALPHABETUM, which seems to have the most complete set of characters, does not have the correct italics.

Sylf, your question is a bit cryptic. I'll also be cryptic. There is in Brill Italic the substitution

    sub \uni043D by \uni043F.Serbian ;


where I would have expected \uni043F on the left hand side. Here are the roman and the corresponding italic obtained with XeLaTeX.

Added later on (I guess it is now less cryptic).
Also XeLaTeX does not accept selecting the Serbian language for the font family Brill; after calling
\setmainfont[Script=Cyrillic,Language=Serbian]{Brill}
XeLaTeX does not give the Serbian italic when using \textit, probably because Serbian is not defined for the regular. I had to declare a separate font for the italic to get it above. I don't know if this is a XeLaTeX bug or not but Arno has Cyrillic/Serbian also for the roman, avoiding such a problem (and giving a different looking output for cyrillic small letter p and cyrillic small letter n).

Sylph, I do not work with Serbian glyphs. But let me reference an older thread about PDFs made in Word 2010. The problem was that with Opentype Postscript flavor fonts, MS Word always converted to curves when going to PDF, regardless of the embeddability of the font.
I do not know (but I would like to know) if this was fixed in Word 2013. I do not know what Word version you are using. I do not know if this is related to what you are seeing. Glad I could help!
http://typophile.com/node/72404
Read what Si_Daniels has to say in the middle.

Thank you, Michel and J.!

So judging by what you two wrote this is a typeface issue and a Microsoft Word issue. The Word I'm using is from the Office 2013. Which means that whatever the issue was, it isn't corrected.

As for Brill: why would a Cyrillic n in italics produce a correct Serbian cursive Cyrillic p?

And also, I was wrong – there is only one typeface so far in the World that can both produce the correct italics and correctly combine the combining diacritics. That is what I meant by the line above. It is Gentium.

As for Brill: why would a Cyrillic n in italics produce a correct Serbian cursive Cyrillic p?

Because the Unicode character 043D is

043D	CYRILLIC SMALL LETTER EN


and the substitution rule in Brill as extracted above from the italic using FrontForge says to substitute uni043D, i.e. cyrillic small letter en, with uni043F.Serbian i.e. the Serbian variant of Unicode character 043F, namely

043F	CYRILLIC SMALL LETTER PE


That is how Unicode fonts work. The font contains substitution tables to apply for given scripts and languages.

How that particular substitution appeared that way in Brill is a bit mysterious to me.

Definite bug in the OTL GSUB code for the Serbian pe. The VOLT source has a typo and the lookup currently reads
c.en -> c.pe.Serbian
c.pe -> c.pe.Serbian

Thanks for catching that. I'll get a fix to Brill a.s.a.p.

“there is only one typeface so far in the World that can both produce the correct italics and correctly combine the combining diacritics. That is what I meant by the line above. It is Gentium.”

What is the problem with DejaVu Serif?

@Sylph: Your picture before “Why does it happen?” is

and contains the italic cyrillic small letter letter sha, “ш ”. In the Wiki article Serbian alphabet there is the following picture where the third column is meant to correspond to the Serbian italic.

Is there any font with an underlined italic cyrillic small letter sha? Is that underline documented?

Is there any font with an underlined italic cyrillic small letter sha?

Ok, I found one in GNU's Free Serif Italic, http://ftp.gnu.org/gnu/freefont/, as a stylistic alternate.

“The only typefaces…”: Andron Cyrillic

So is this fixed Brill getting released or is 2.02 the version available online?