International Civil Aviation Organisation ( ICAO). Is just that an Organisation of contracting states. As far as I am aware the languages listed ( English, French, Spanish and Russian) are simply the languages that are adopted for internal and external publication of Reports recommendations etc). It has nothing to do with restricting the languages that can be used on the radio.
There is a lengthy explanation of the history and structure of ICAO at its website together with a list of contracting states and much additional information. I think "ICAO" is often used as a bit of a red herring in regard to aviation laws and procedures. It frequently makes recommendations that individual states may or may not adopt. A bit like the United nations in that respect.
You often see threads on these boards from individuals claiming to have "an ICAO pilots licence" when in fact there is no such thing. They mean they have a pilots licence issued by an ICAO member state, which may be interesting but usually has little meaningful significance.
In answer to your question, I have no doubt there are many examples of poor communication that have eroded safety in the past and they will probably continue to do so to a greater or lesser degree in the future. Even where English is the sole language of communication, it is not usually the states primary language, nor is it necessarily understood to a level beyond the bounds of necessity. Technology such as FANS and datalink may well positively address these problems in the future.
Whatever may be the shortcomings of the system, beware the idea "pig headed arrogance". If a universal standard were ever to be agreed and mandated it might be Spanish, or mandarin Chinese, both of which are very wide spoken languages ?