CQ (which sounds like "seek you") is still used in amateur radio. CQD is just "seek you distress". SOS was chosen because of it's distinctive sound although in my humble opinion CQ is pretty distintive sounding in morse code as well. BTW Phillips did use SOS towards the end. For those interested the BBC did a documentary about the morse code transmissions from Titanic.
When you ask how many non-Europeans knew what CQD was I suspect you meant non-English speakers since I don't think a lot of non-Europeans had wireless telegraph. I think they knew what it meant but didn't like a standard based on what things sound like in English.
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