(Not a Teacher)
I don't think the 'sh' and 'zh' change much across different accents and dialects. Also, pronouncing "Asia" or "Indonesia" with a "sh" sounds very strange to me. For 's' and 'z', there might be odd words like 'eczema' where you might hear an 's' sound instead of a 'z', but I don't believe it's at all common to switch them in any native speaking dialect.
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