LibreOffice not recognizing fonts in OSX

I recently installed Source Sans Pro and Fira Sans on my Mac (OS X 10.10 Yosemite). Source Sans Pro has 12 weights (Regular, Bold, Italic, Bold Italic, Light, Extra Light, etc…) and Fira Sans has 32 (absolutely awesome for a Free font.) In all apps except LibreOffice, they both behave wonderfully. In LibreOffice, only 10 weights of Source Sans Pro display in the Character selection dialogue, and only 15 weights of Fira Sans. All variants work fine in every other app, so the font files are not corrupt and the problem is in LibreOffice. Even weirder is the fact that the set of weights displayed in LibreOffice Still (4.2.8) is not always the same subset of the full list of weights. (Fresh - 4.3.5 - is always missing ExtraLight and ExtraLight Italic.) Which fonts are missing changes from one time I look at the character selection dialogue to the next! Only the number of missing fonts is constant. For example, currently Source Sans Pro Extralight and Extralight Italic are missing, but last time I installed the font, the missing ones were Light and Demibold Italic.

LibreOffice keeps its own bundled fonts separate from the system fonts. For example, it comes bundled with a few weights of Source Sans Pro (all twelve weights in LibreOffice Fresh 4.3.5), but Source Sans Pro is not visible or searchable in Font Book (Font Book is the OS X font manager). Liberation Sans is also not present in Font Book. This isn’t a problem (If I want fonts in my system, I’ll just install them!) but I think it may be related.
UPDATE: I looked in the LibreOffice font directory and it turns out that LibreOffice 4.3.5 now bundles all weights of Source Sans Pro, including ExtraLight and ExtraLight Italic. However, those two are still invisible in the character selection dialogue. It seems to me that LibreOffice has some sort of preconception that “SOURCE SANS PRO HAS ONLY TEN WEIGHTS.”

Neither the fonts that came with my system nor the ones bundled with LibreOffice are sufficient for my needs (I need weights of Source Sans Pro that are not bundled in LibreOffice Still and are inaccessible in Fresh regardless of whether I install the font family system-wide), so I really need all the help with this I can get. Is there some way to fix this without having to slog through the bug report system? I don’t trust myself to be knowledgable enough for that. Is there some cache to clear or file to change? I need a way out of this ASAP! Thanks in advance for any help you can give.

I am not a Mac expert but in Windows LibO accesses all fonts installed; for a Mac I assume the same because of the basic behavior that all application should be able to access the same installed fonts.

Here are some links which might help you:

You said “in Windows LibO accesses all fonts installed; for a Mac I assume the same.” This is indeed what is supposed to happen. The question is how to make it happen if for some reason it doesn’t.

I stated in the original question that I suspect LibreOffice on Mac uses fonts that are not installed in the system. Liberation Serif, Sans and Mono are NOT PRESENT in the system or user font directories yet are still usable by LibreOffice. I figured that meant it keeps its fonts in a separate directory. Your first link confirms that. I may be able to circumvent the problem for the time being by modifying the directory cited and installing fonts directly into it.

UPDATE: The LibreOffice font directory contains all twelve Source Sans Pro variants, just like the system directory does. Still, only ten weights display in LibreOffice.

This is a known problem under Mac OSX. Refer this answer.

EDIT: Comment 12 in bug fdo#69254 indicates the new font API under Mac OSX is not yet fully supported. This seems to be the source of the problem i.e., incomplete listing of font variants/weights.

This is not the same bug. I never expected all weights to appear in the font dropdown menu. Only one weight, regular, appears there. That is the way it should be.
The Dialog I am talking about is accessible by right clicking anywhere in the formatting toolbar to view extra buttons, and clicking on “Character.”

This gives a separate window with three columnar lists and a preview beneath. The columns are, from right to left: Font, Weight, and Font Size. Source Sans Pro is supposed to have twelve weights but only ten display in the center column. ExtraLight and ExtraLight Italic are missing. This only happens with LibreOffice bundled or user-installed fonts. Preinstalled system fonts with lots of weights, like Helvetica Neue, have all weights available in that window.

The main difference between that bug and this one is that that one was about missing fonts. This is about font variants/weights like “Source Sans Pro Light”, or “Fira Sans Book”. Some variants are simply not accessible, probably due to some internal LibO registry that does not know of their existence. In my opinion, they should probably fix this one before they even start thinking about Bug 66792, as it would rely on the fix for this.

Sorry about the comment swarm. Bug 69254 may be related underneath, now that I look at it again, but the question you linked to is unrelated. In other words, a not-so-good answer to that question would have made a much more direct (but still hopelessly oblique) answer to this question.

Yes. As comment 12 in bug fdo#69254 indicates the new font API under Mac OSX is not yet fully supported. Where I wrote my prior answer on this issue the situation (with respect to bug reports) was significantly more confused due to the number of duplicate reports.