From personal experiences, unlike EK, QR seem much less bothered promoting staff language skills, and even on flights to places like China, there haven't been any annoucements in Chinese, even with Chinese speaking FAs onboard!

I assume that all crew with specialist language skills are known to QR, and they might *try* to match up the languages with the routes. Sometimes it works, sometimes it doesn't. Some airlines have specific language bases (e.g. BA has a Spanish language crew based in MEX, whom only do LHR-Latin America routes), but I think QR has all crew going everywhere, subject to aircraft certification and visas (I think USA/Canada needs a visa, and only some crew have these).

I think the only langauge that QR really care about catering to (other than English) is Arabic, despite the fact that on some routes, there can't be more than a handful of Arabic speakers, and massively out numbered by a 3rd langauge (e.g. Korean/Japanese/Chinese/Spanish).