I'm a bit at a loss where to put my hooks. My requirement is to have a checkbox in the page (already there) that tells my module to pull fields (i.e. body, headline etc., but possibly others too in the near future) from the default language, no matter if there's a value set in the current language, and apply some replacement before rendering (think HannaCode-like, though with a whole dictionary database for technical terms behind it).
Now, I'm unsure where to hook. I've looked through the LanguageSupport modules and tried to spy in HannaCode, but I've not been able to wrap my head around all the getLanguage..., getFormatted... and whatnot hookable methods involved. Attempts at overriding LanguageSupportFIelds::hookFieldtypeFormatValue and extending its logic somehow ended up with an endless recursion. If anybody could give me a few pointers (or method names) I should look for, this would be great.