Peter,
I did try it in the UI with "\s" and in a script with "\\s".
But with this expression I couldn't find something like "~>" (thin space).
I have detected this while writing some lines for FindChangeByList.jsx.
The following lines should put a thin space between a single or two character(s) followed by a dot followed by a single or two character(s) followed by a dot. (e.g. "e.g." -> "e.|g."; "J.Ch. Peirce" -> "J.|Ch. Peirce", "B. C. E." -> "B.|C.|E.", ...)
As you told that \s captures all white space in the english version of ID, this seems to be a bug in the german version.