> strange is that the matches() regex allows only decimal values as  
> range 592 represents here hex 0250 

The regex syntax doesn't allow any numeric references in decimal or hex.
You have to use a character. However before being passed to XPath, teh
attribute is parsed by an XML parser so you can use any XML syntax for
that character, named entity references (as defined in a dtd) teh
character in the file's encoding,  decimal character references (as you
have) or hex character references, which would use the & # x 0 2 5 0 ;
syntax.

 match="*[matches(substing(text()[1], 1, 1), '[ɐ-𘚟]')]">

It's probably simpler to just restrict the regex to the first character,
rather than use substring:


 match="*[matches(., '^[ɐ-𘚟]')]">

David