I believe the issue of which you ask is about the .ogg Vorbis file format. Unfortunately, Wikia has designated audio files to be uploaded only as this format, so no .mp3, etc.
By "most web browser[s]", I'm guessing you mean Internet Explorer and Safari. It is expected, and completely normal, for them not to work, as they do not contain the software necessary to support the format. (I noted this under every audio addition)
In other words, uploading a variation of the same file format would be utterly usesless and redundant. So unless Wikia begins allowing other audio formats, there's no getting around this issue. Until then, users will have to stick to other browsers.
No, I can't play your files in Chromium based browser. As for IE and Spartan, well, SNAFU.
Actually, I still didn't know what actually causing this behavior. I can't play your ogg files directly on Charlotte wiki, either on article pages, file pages or the actual file URI; but if I download it manually and open it with browser, it will play.
Strangely, I still can directly play all ogg files I upload in Kanon wiki (and other sites). So, either there's some weird encoding issues or site-specific bug.
I'll look further into it later, sorry if I bother you.
Ah, and all vorbis-encoded ogg are VBR by design, silly me.