SIL Graphite is only supported on the Windows or Linux builds. It would be great if SIL Graphite were supported on the Mac OS X build as well. A LibreOffice document with formatting that uses a SIL Graphite feature, e.g. with "Gentium Plus:carn=1", will only work on Windows or Linux builds. Opening the same document on Mac OS X will break the formatting. That should not be. While Apple provides its own technology with similar capabilities to SIL Graphite, Apple Advanced Typography (AAT), most fonts that have SIL Graphite features do not offer AAT features. And even if they did, the Mac OS X build does not have the capability of controlling AAT features, whereas the SIL Graphite features can be controlled with expansions to the font name (e.g. "Gentium Plus:carn=1" instead of plain "Gentium Plus").
Thank you for filing this enhancement request.
Created attachment 119539 [details] Graphite test document (Gentium Plus font embedded) Adding a test document. It shows two lines with the string _Ťť Ďď Ľľ_: First in the font _Gentium Plus_, then in the font _Gentium Plus:carn=1_. On Windows or Linux, both lines will be displayed in the font _Gentium Plus_. On the second line, the SIL Graphite feature _carn_ is set to "1", so all diacritics have the form of a caron (ˇ). On Mac OS X, only the first line will be displayed in the font _Gentium Plus_, while the second line will be displayed in a fallback font.
Created attachment 119540 [details] Graphite test document, proper display (Lubuntu 15.04) This is a screenshot of what the Graphite test document is supposed to look like. It is made on Lubuntu 15.04, but on Windows 10, it looks the same. Mac OS X 10.11 messes up the second line.
Created attachment 124436 [details] Faulty display of the Graphite test document on OS X 10.11.4, LibreOffice 5.1.2.2 Still no changes; the display is flawless on Linux or Windows builds, but continues to be faulty on the Mac OS X build.